A computer is a device that can be instructed to carry out an arbitrary set of arithmetic or logical operations automatically. Their ability of computers to follow a sequence of operations, called a program, make computers very flexible and useful. Such computers are used as control systems for a very wide variety of industrial and consumer devices. This includes simple special purpose devices like microwave ovens and remote controls, factory devices such as industrial robots and computer assisted design, but also in general purpose devices like personal computers and mobile devices such as smart phones. The Internet is run on computers and it connects millions of other computers. Computer Capabilities Speed and accuracy capabilities: A computer works one step at a time. It can add, subtract, compare digits and letters, move and copy numbers and letters. There’s nothing profound in these operations. What is significant is the computer speed. This speed is measured in milliseconds, microseconds, nanoseconds and Pico seconds (Recent study says computer speed is being doubled every six months). The speed required for computers to execute a basic operation like addition varies from a few microseconds for the smallest machines to 80 nano seconds or less for the larger ones. Thus, the slowest computers can perform hundreds of thousands of additions in a second while the largest systems can compute several million additions in the same period. Data manipulating capability: The first computers were built to manipulate numbers in order to solve arithmetic problems. Along with numbers, we also use alphabets and different symbols in our daily life. Luckily, early computer experts made the important discovery that a machine that can accept, store and process numbers can also be used to manipulate non-numeric symbols. Manipulating these familiar symbols is possible if an identifying code number is assigned to the symbol to be stored and processed. Thus, the letter A can be represented by a code, so can the letter B, the addition symbol and so on. Of course, one must give the computer instructions for it to manipulate the coded and stored symbols in a desired way. Data - versus – information: The word “data” is the plural of datum, which means fact. Data then, are facts or raw material of information. Data are indicated by symbols. Data arranged in ordered or useful form is called information. That is, information is relevant knowledge produced as output after data processing operations and acquired by people to enhance understanding and to achieve specific goals. The following are the stages in processing of raw data to provide information: 1. Data Collection, 2. Raw data input, 3. Data Processing, 4. Information & 5. End user judgment and measures. Data Processing activities: Data processing consists of gathering the raw data input, evaluating and bringing order to it and placing it in proper perspective so that useful information is produced. All data processing, whether done by hand or computer system consists or three basic activities: capturing the input data, manipulating the data and managing the output results.

LIMITATION OF COMPUTER Computer has done this and that. Actually this is not the computer which has done this but the user. Despite its various features, a computer does have the following limitations: a. No Self Intelligence Today, a computer is able to do a work which is impossible for man. Computers are used to do risky and dangerous work and where sharp actually is needed. But it does not have any intelligence of its own. It works according to the instruction only. b. No Decision-Making power Computer cannot take any decision of its own. It does only those tasks which are already instructed to it. c. No learning power. Computer has no learning power. Once you give instructions to a computer how to perform a task, the very task is cannot perform if you do not give it any instructions for the next time. For example, when you are taught how to solve a problem and it same type of problem is given to you to solve, then you can do it because you have learned how to solve the problem. History of Computers The abacus was an early aid for mathematical computations. Its only value is that it aids the memory of the human performing the calculation. A skilled abacus operator can work on addition and subtraction problems at the speed of a person equipped with a hand calculator (multiplication and division are slower). The abacus is often wrongly attributed to China. In fact, the oldest surviving abacus was used in 300 B.C. by the Babylonians. The abacus is still in use today, principally in the Far East. A modern abacus consists of rings that slide over rods, but the older one pictured below dates from the time when pebbles were used for counting (the word "calculus" comes from the Latin word for pebble). Generations of Computers First Generation (1940-1956) Vacuum Tubes The first computers used vacuum tubes for circuitry and magnetic drums for memory, and were often enormous, taking up entire rooms. They were very expensive to operate and in addition to using a great deal of electricity, the first computers generated a lot of heat, which was often the cause of malfunctions. First generation computers relied on machine language, the lowest-level programming language understood by computers, to perform operations, and they could only solve one problem at a time, and it could take days or weeks to set-up a new problem. Input was based on punched cards and paper tape, and output was displayed on printouts. The UNIVAC and ENIAC computers are examples of first-generation computing devices. The UNIVAC was the first commercial computer delivered to a business client, the U.S. Census Bureau in 1951.

Second Generation (1956-1963) Transistors Transistors replace vacuum tubes and ushered in the second generation of computers. The transistor was invented in 1947 but did not see widespread use in computers until the late 1950s. The transistor was far superior to the vacuum tube, allowing computers to become smaller, faster, cheaper, more energy-efficient and more reliable than their first-generation predecessors. Though the transistor still generated a great deal of heat that subjected the computer to damage, it was a vast improvement over the vacuum tube. Second-generation computers still relied on punched cards for input and printouts for output. Second-generation computers moved from cryptic binary machine language to symbolic, or assembly, languages, which allowed programmers to specify instructions in words. High-level programming languages were also being developed at this time, such as early versions of COBOL and FORTRAN. These were also the first computers that stored their instructions in their memory, which moved from a magnetic drum to magnetic core technology. The first computers of this generation were developed for the atomic energy industry. Third Generation (1964-1971) Integrated Circuits The development of the integrated circuit was the hallmark of the third generation of computers. Transistors were miniaturized and placed on silicon chips, called semiconductors, which drastically increased the speed and efficiency of computers. Instead of punched cards and printouts, users interacted with third generation computers through keyboards and monitors and interfaced with an operating system, which allowed the device to run many different applications at one time with a central program that monitored the memory. Computers for the first time became accessible to a mass audience because they were smaller and cheaper than their predecessors. Fourth Generation (1971-Present) Microprocessors The microprocessor brought the fourth generation of computers, as thousands of integrated circuits were built onto a single silicon chip. What in the first generation filled an entire room could now fit in the palm of the hand. The Intel 4004 chip, developed in 1971, located all the components of the computer—from the central processing unit and memory to input/output controls—on a single chip. In 1981 IBM introduced its first computer for the home user, and in 1984 Apple introduced the Macintosh. Microprocessors also moved out of the realm of desktop computers and into many areas of life as more and more everyday products began to use microprocessors. As these small computers became more powerful, they could be linked together to form networks, which eventually led to the development of the Internet.

Fourth generation computers also saw the development of GUIs, the mouse and handheld devices. Fifth Generation (Present and Beyond) Artificial Intelligence Fifth generation computing devices, based on artificial intelligence, are still in development, though there are some applications, such as voice recognition, that are being used today. The use of parallel processing and superconductors is helping to make artificial intelligence a reality. Quantum computation and molecular and nanotechnology will radically change the face of computers in years to come. The goal of fifth-generation computing is to develop devices that respond to natural language input and are capable of learning and selforganization. Classes/categories of Computer · Analog Computer – operates on continuous physical or electrical magnitudes, measuring ongoing continuous analog quantities such as voltage, current, temperature, and pressure. Selected physiologic monitoring equipment, which accepts continuous input/output signals, is in the analog class of computers. An example of these machines in the clinical setting includes heart monitors and fetal monitors. An analog computer handles data in continuously variable quantities rather than breaking the data down into discrete digital representations. · Digital Computer – The digital computer, on the other hand, operates in discrete discontinuous numerical digits using the binary numbering system. It represents data using discrete values for all data. Its data are represented by numbers, letters and symbols rather than by waveforms such as on a heart monitor. Most of the computers used in the health care industry for charting and decision support are digital computers. · Hybrid Computer – The hybrid computer, as its name implies, contains features of both the analog and the digital computer. It is used for specific applications, such as complex signal processing and other engineering – oriented applications. It is also found in some monitoring equipment that converts analog signals to digital ones for data processing. For example, physiologic monitors that are able to capture the heart waveform and also to measure the core body temperature at specific times of the shift are actually hybrid computers. Some physiologic research providers can make use of hybrid computers that have analog ability to capture waveforms of physiologic monitors and convert them into digital format suitable for analysis.

Types of Computers Computers can be generally classified by size and power. Some of them are Ø Supercomputers - largest type of computer - “number cruncher” Ø Mainframes - Can serve a large number of users at a time. - As compared with a desktop PC, a mainframe has an extremely large memory capacity and fast operating and processing time and it can process a large number of functions (multiprocessing) at one time. Ø Microcomputers - Hospital nursing departments are using PCs to process specific applications such as patient classification, nurse staffing and management applications. Ø

Handheld Computers - used by nurses when charting - used to take notes by bedside

Uses of Computers: Computers have become an essential part of modern human life. Since the invention of computer they have evolved in terms of increased computing power and decreased size. Owing to the widespread use of computers in every sphere, Life in today’s world would be unimaginable without computers. They have made human lives better and happier. There are many computer uses in different fields of work. Engineers, architects, jewelers, and filmmakers all use computers to design things. Teachers, writers, and most office workers use computers for research, word processing and emailing. Small businesses can use computers as a point of sale and for general record keeping. Computers Aid at Education: Computers have its dominant use in the education field which can significantly enhance performance in learning. Even distance learning is made productive and effective through internet and video-based classes. Researchers have massive usage of these computers in their work from the starting to till the end of their scholarly work. Computers in our Health and Medicine: Most of the medical information can now be digitized from the prescription to reports. Computation in the field of medicine allows us tooffer varied miraculous therapies to the patients. ECG’s, radiotherapy wasn’t possible without computers. Aid of Computers at Financial Institutions: We know well that computers are being used by the financial institutions like banks for different purposes. The foremost important thing is to store

information about different account holders in a database to be available at any time. Keeping the records of the cash flow, giving the information regarding your account, Computers for our Pass time: Computers are now the major entertainers and the primary pass time machines. We can use computers for playing games, watching movies, listening to music, drawing pictures. Computers are a part of our Transport System: With internet on computers we can know the details of the buses or trains or the flight available to our desired destination. The timings and even the updates on the delay can also be known through these computers. We can book our tickets through online. Staff of the transport system will keep a track of the passengers, trains or flight details, departure and arrival timings by using computers. Inevitable use of Computers in Business and Corporate Stages: Every single information shared can be recorded by using computer. Official deals and the issues were made even through online. We use email system to exchange the information. It has wide uses in marketing, stock exchanges and bank. Even the departmental stores can’t run effectively without computer. Wonders of Computer in E-Commerce: Electronic mail is the revolutionary service offered by the computes. Video Conferencing is also another major advantage. Electronic shopping through online shopping added favor to purchaser and merchants. Electronic banking is now at your hand where every bank has online support for transaction of monetary issues. You can easily transfer your money anywhere even from your home. Computer at our Defense: Computers are the main tools which help in developing missiles and other equipment in the deference system. Designing and the maintenance are possible only through computers. Computer builds the links between the soldiers and commanders through the satellite. Construction of weapons and controlling their function is not possible without the aid of computers. The list of the criminals and the records of the cops are maintained regularly in the system. Computer is today’s Designer: As per the title, computers aid in designing buildings, magazines, prints, newspapers, books and many others. The construction layouts are designed beautifully on system using different tools and software’s.

Before a computer can process your data, you need some method to input the data into the machine. The device you use will depend on what form this data takes (be it text, sound, artwork, etc.). Similarly, after the computer has processed your data, you often need to produce output of the results. This output could be a display on the computer screen, hardcopy on printed pages, or even the audio playback of music you composed on the computer. Input Devices: a) Graphics Tablets b) Cameras c) Video Capture Hardware d) Trackballs e) Barcode reader f) Digital camera g) Gamepad h) Joystick i) Keyboard j) Microphone k) MIDI keyboard l) Mouse (pointing device) m) Scanner n) Webcam o) Touch pads p) Pen Input q) Microphone r) Electronic Whiteboard s) OMR t) OCR u) Punch card reader v)MICR (Magnetic Ink character reader) w) Magnetic Tape Drive OUTPUT DEVICES: 1. Monitor (LED, LCD, CRT etc) 2. Printers (all types) 3. Plotters 4. Projector 5. LCD Projection Panels 6. Computer Output Microfilm (COM) 7. Speaker(s) 8. Head Phone 9. Visual Display Unit 10. Film Recorder 11. Microfiche

Your personal computer is a type of digital electronic computer. It is called digital because all of the information inside it is represented and manipulated as numbers (the original meaning of “digit” is “finger,” and since people often count using their fingers, the term digit also came to be applied to numbers). All of the numbers in a spreadsheet, all of the text characters in a Word document, all of the pictures and sounds stored in a computer, are ALL represented as numbers. The microprocessor is the component of the personal computer that does the actual processing of data. A microprocessor is a central processing unit (CPU) that fits on one microchip. It is the “brain” of the computer, but that is a rather pretentious terms since it really just a very complex switching circuit that executes simple instructions very rapidly. SOFTWARE Computer software, or simply software, is that part of a computer system that consists of encoded information or computer instructions, in contrast to the physical hardware from which the system is built. System software consists of the operating system, which has a graphic user interface that allows the user to interact with it, and utilities. The operating system and utilities work together to move data between the computer's processor, memory, storage and peripherals. They serve as a back end for a computer's operation. Application software is readily apparent and visible to the user. It includes the Web browsers, business productivity programs, games and other applications that make the computer useful.

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Utilities, which are computer programs designed to assist users in the maintenance and care of their computers. Examples include disk utilities like defragmenters, compressors and cleaners. There are also operating system utilities such as antivirus programs, registry cleaners and system restoration programs. Malicious software or malware, which is software that is developed to harm and disrupt computers. As such, malware is undesirable. Malware is closely associated with computer-related crimes, though some malicious programs may have been designed as practical jokes.

DOS is an Operating System. It works as an interpreter between user and computer. We give English like commands and it converts it into machine language and after the computer has processed the information, returns the results to you in English. Ms. Dos consist of four essential programs and a set of additional utilities. Components of MS-DOS MS-DOS consists of four essentials programs and a set of additional utilities. Four main programs are 1. 2. 3. 4.

Boot Record IO.SYS MSDOS.SYST COMMAND.COM

A network consists of two or more computers that are linked in order to share resources (such as printers and CDs), exchange files, or allow electronic communications. The computers on a network may be linked through cables, telephone lines, radio waves, satellites, or infrared light beams. Two very common types of networks include:  Local Area Network (LAN)  Wide Area Network (WAN) You may also see references to a Metropolitan Area Networks (MAN), a Wireless LAN (WLAN), or a Wireless WAN (WWAN). Local Area Network A Local Area Network (LAN) is a network that is confined to a relatively small area. It is generally limited to a geographic area such as a writing lab, school, or building. Computers connected to a network are broadly categorized as servers or workstations. Servers are generally not used by humans directly, but rather run continuously to provide "services" to the other computers (and their human users) on the network. Services provided can include printing and faxing, software hosting, file storage and sharing, messaging, data storage and retrieval, complete access control (security) for the network's resources, and many others.

Workstations are called such because they typically do have a human user which interacts with the network through them. Workstations were traditionally considered a desktop, consisting of a computer, keyboard, display, and mouse, or a laptop, with with integrated keyboard, display, and touchpad. With the advent of the tablet computer, and the touch screen devices such as iPad and iPhone, our definition of workstation is quickly evolving to include those devices, because of their ability to interact with the network and utilize network services. Servers tend to be more powerful than workstations, although configurations are guided by needs. For example, a group of servers might be located in a secure area, away from humans, and only accessed through the network. In such cases, it would be common for the servers to operate without a dedicated display or keyboard. However, the size and speed of the server's processor(s), hard drive, and main memory might add dramatically to the cost of the system. On the other hand, a workstation might not need as much storage or working memory, but might require an expensive display to accommodate the needs of its user. Every computer on a network should be appropriately configured for its use. On a single LAN, computers and servers may be connected by cables or wirelessly. Wireless access to a wired network is made possible by wireless access points (WAPs). These WAP devices provide a bridge between computers and networks. A typical WAP might have the theoretical capacity to connect hundreds or even thousands of wireless users to a network, although practical capacity might be far less. Nearly always servers will be connected by cables to the network, because the cable connections remain the fastest. Workstations which are stationary (desktops) are also usually connected by a cable to the network, although the cost of wireless adapters has dropped to the point that, when installing workstations in an existing facility with inadequate wiring, it can be easier and less expensive to use wireless for a desktop. Wide Area Network Wide Area Networks (WANs) connect networks in larger geographic areas, such as Florida, the United States, or the world. Dedicated transoceanic cabling or satellite uplinks may be used to connect this type of global network. Using a WAN, schools in Florida can communicate with places like Tokyo in a matter of seconds, without paying enormous phone bills. Two users a half-world apart with workstations equipped with microphones and a webcams might teleconference in real time. A WAN is complicated. It uses multiplexers, bridges, and routers to connect local and metropolitan networks to global communications networks like the Internet. To users, however, a WAN will not appear to be much different than a LAN.

Advantages of Installing a School Network User access control. Modern networks almost always have one or more servers which allows centralized management for users and for network resources to which they have access. User credentials on a privately-owned and operated network may be as simple as a user name and password, but with everincreasing attention to computing security issues, these servers are critical to ensuring that sensitive information is only available to authorized users. Information storing and sharing. Computers allow users to create and manipulate information. Information takes on a life of its own on a network. The network provides both a place to store the information and mechanisms to share that information with other network users. Connections. Administrators, instructors, and even students and guests can be connected using the campus network. Services. The school can provide services, such as registration, school directories, course schedules, access to research, and email accounts, and many others. (Remember, network services are generally provided by servers). Internet. The school can provide network users with access to the internet, via an internet gateway. Computing resources. The school can provide access to special purpose computing devices which individual users would not normally own. For example, a school network might have high-speed high quality printers strategically located around a campus for instructor or student use. Flexible Access. School networks allow students to access their information from connected devices throughout the school. Students can begin an assignment in their classroom, save part of it on a public access area of the network, then go to the media center after school to finish their work. Students can also work cooperatively through the network. Workgroup Computing. Collaborative software allows many users to work on a document or project concurrently. For example, educators located at various schools within a county could simultaneously contribute their ideas about new curriculum standards to the same document, spreadsheets, or website.

Disadvantages of Installing a School Network Expensive to Install. Large campus networks can carry hefty price tags. Cabling, network cards, routers, bridges, firewalls, wireless access points, and software can get expensive, and the installation would certainly require the services of technicians. But, with the ease of setup of home networks, a simple network with internet access can be setup for a small campus in an afternoon. Requires Administrative Time. Proper maintenance of a network requires considerable time and expertise. Many schools have installed a network, only to find that they did not budget for the necessary administrative support. Servers Fail. Although a network server is no more susceptible to failure than any other computer, when the files server "goes down" the entire network may come to a halt. Good network design practices say that critical network services (provided by servers) should be redundant on the network whenever possible. Cables May Break. The Topology chapter presents information about the various configurations of cables. Some of the configurations are designed to minimize the inconvenience of a broken cable; with other configurations, one broken cable can stop the entire network. Security and compliance. Network security is expensive. It is also very important. A school network would possibly be subject to more stringent security requirements than a similarly-sized corporate network, because of its likelihood of storing personal and confidential information of network users, the danger of which can be compounded if any network users are minors. A great deal of attention must be paid to network services to ensure all network content is appropriate for the network community it serves.

In computer networking, topology refers to the layout of connected devices. This article introduces the standard topologies of networking. Topology in Network Design Think of a topology as a network's virtual shape or structure. This shape does not necessarily correspond to the actual physical layout of the devices on the network. For example, the computers on a home network may be arranged in a circle in a family room, but it would be highly unlikely to find a ring topology there. Network topologies are categorized into the following basic types:  bus  ring  star  tree  mesh More complex networks can be built as hybrids of two or more of the above basic topologies. Bus Topology Bus networks (not to be confused with the system bus of a computer) use a common backbone to connect all devices. A single cable, the backbone functions as a shared communication medium that devices attach or tap into with an interface connector. A device wanting to communicate with another device on the network sends a broadcast message onto the wire that all other devices see, but only the intended recipient actually accepts and processes the message. Ethernet bus topologies are relatively easy to install and don't require much cabling compared to the alternatives. 10Base-2 ("ThinNet") and 10Base-5 ("ThickNet") both were popular Ethernet cabling options many years ago for bus topologies. However, bus networks work best with a limited number of devices. If more than a few dozen computers are added to a network bus, performance problems will likely result. In addition, if the backbone cable fails, the entire network effectively becomes unusable.

Ring Topology In a ring network, every device has exactly two neighbors for communication purposes. All messages travel through a ring in the same direction (either "clockwise" or "counterclockwise"). A failure in any cable or device breaks the loop and can take down the entire network.

Star Topology Many home networks use the star topology. A star network features a central connection point called a "hub node" that may be a network hub, switch or router. Devices typically connect to the hub with Unshielded Twisted Pair (UTP) Ethernet.

Tree Topology A tree topology joins multiple star topologies together onto a bus. In its simplest form, only hub devices connect directly to the tree bus and each hub functions as the root of a tree of devices. This bus/star hybrid approach supports future expansion of the network much better than a bus (limited in the number of devices due to the broadcast traffic it generates) or a star (limited by the number of hub connection points) alone.

Mesh Topology Mesh topology introduces the concept of routes. Unlike each of the previous topologies, messages sent on a mesh network can take any of several possible paths from source to destination. (Recall that even in a ring, although two cable paths exist, messages can only travel in one direction.) Some WANs, most notably the Internet, employ mesh routing.

Summary Topology remains an important part of network design theory. You can probably build a home or small business computer network without understanding the difference between a bus design and a star design, but becoming familiar with the standard topologies gives you a better understanding of important networking concepts like hubs, broadcasts, and routes.

The Internet is the global system of interconnected computer networks that use the Internet protocol suite (TCP/IP) to link billions of devices worldwide. It is a network of networks that consists of millions of private, public, academic, business, and government networks of local to global scope, linked by a broad array of electronic, wireless, and optical networking technologies. The Internet carries an extensive range of information resources and services, such as the inter-linked hypertext documents and applications of the World Wide Web (WWW), electronic mail, newsgroups, voice over IP telephony, and peer-to-peer networks for file sharing. The origins of the Internet date back to research commissioned by the United States federal government in the 1960s to build robust, fault-tolerant communication via computer networks. The primary precursor network, the ARPANET, initially served as a backbone for interconnection of regional academic and military networks in the 1980s. The funding of the National Science Foundation Network as a new backbone in the 1980s, as well as private funding for other commercial extensions, led to worldwide participation in the development of new networking technologies, and the merger of many networks. The linking of commercial networks and enterprises by the early 1990s marks the beginning of the transition to the modern Internet, and generated a sustained exponential growth as generations of institutional, personal, and mobile computers were connected to the network. Although the Internet was widely used by academia since the 1980s, the commercialization incorporated its services and technologies into virtually every aspect of modern life. Services The Internet carries many network services, most prominently mobile apps such as social media apps, the World Wide Web, electronic mail, multiplayer online games, Internet telephony, and file sharing services. World Wide Web Many people use the terms Internet and World Wide Web, or just the Web, interchangeably, but the two terms are not synonymous. The World Wide Web is the primary application that billions of people use on the Internet, and it has changed their lives immeasurably. However, the Internet provides many other services. The Web is a global set of documents, images and other resources, logically interrelated by hyperlinks and referenced with Uniform Resource Identifiers (URIs). URIs symbolically identifies services, servers, and other databases, and the documents and resources that they can provide. Hypertext

Transfer Protocol (HTTP) is the main access protocol of the World Wide Web. Web services also use HTTP to allow software systems to communicate in order to share and exchange business logic and data. Communication Email is an important communications service available on the Internet. The concept of sending electronic text messages between parties in a way analogous to mailing letters or memos predates the creation of the Internet. Pictures, documents, and other files are sent as email attachments. Emails can be cc-ed to multiple email addresses. Internet telephony is another common communications service made possible by the creation of the Internet. VoIP stands for Voice-over-Internet Protocol, referring to the protocol that underlies all Internet communication. The idea began in the early 1990s with walkie-talkie-like voice applications for personal computers. In recent years many VoIP systems have become as easy to use and as convenient as a normal telephone. The benefit is that, as the Internet carries the voice traffic, VoIP can be free or cost much less than a traditional telephone call, especially over long distances and especially for those with always-on Internet connections such as cable or ADSL. VoIP is maturing into a competitive alternative to traditional telephone service. Interoperability between different providers has improved and the ability to call or receive a call from a traditional telephone is available. Simple, inexpensive VoIP network adapters are available that eliminate the need for a personal computer. Data transfer File sharing is an example of transferring large amounts of data across the Internet. A computer file can be emailed to customers, colleagues and friends as an attachment. It can be uploaded to a website or File Transfer Protocol (FTP) server for easy download by others. It can be put into a "shared location" or onto a file server for instant use by colleagues. The load of bulk downloads to many users can be eased by the use of "mirror" servers or peer-to-peer networks. In any of these cases, access to the file may be controlled by user authentication, the transit of the file over the Internet may be obscured by encryption, and money may change hands for access to the file. The price can be paid by the remote charging of funds from, for example, a credit card whose details are also passed – usually fully encrypted – across the Internet. The origin and authenticity of the file received may be checked by digital signatures or by MD5 or other message digests. These simple features of the Internet, over a worldwide basis, are changing the production, sale, and distribution of anything that can be reduced to a computer file for transmission. This includes all manner of print publications, software products, news, music, film, video, photography, graphics and the other arts. This in turn has caused seismic

shifts in each of the existing industries that previously controlled the production and distribution of these products. Social networking and entertainment Many people use the World Wide Web to access news, weather and sports reports, to plan and book vacations and to pursue their personal interests. People use chat, messaging and email to make and stay in touch with friends worldwide, sometimes in the same way as some previously had pen pals. Social networking websites such as Facebook, Twitter, and Myspace have created new ways to socialize and interact. Users of these sites are able to add a wide variety of information to pages, to pursue common interests, and to connect with others. It is also possible to find existing acquaintances, to allow communication among existing groups of people. Sites like LinkedIn foster commercial and business connections. YouTube and Flickr specialize in users' videos and photographs. While social networking sites were initially for individuals only, today they are widely used by businesses and other organizations to promote their brands, to market to their customers and to encourage posts to "go viral". "Black hat" social media techniques are also employed by some organizations, such as spam accounts and astroturfing. Electronic business Electronic business (e-business) encompasses business processes spanning the entire value chain: purchasing, supply chain management, marketing, sales, customer service, and business relationship. E-commerce seeks to add revenue streams using the Internet to build and enhance relationships with clients and partners. According to International Data Corporation, the size of worldwide ecommerce, when global business-to-business and -consumer transactions are combined, equate to $16 trillion for 2013. A report by Oxford Economics adds those two together to estimate the total size of the digital economy at $20.4 trillion, equivalent to roughly 13.8% of global sales. Telecommuting Telecommuting is the performance within a traditional worker and employer relationship when it is facilitated by tools such as groupware, virtual private networks, conference calling, videoconferencing, and voice over IP (VOIP) so that work may be performed from any location, most conveniently the worker's home. It can be efficient and useful for companies as it allows workers to communicate over long distances, saving significant amounts of travel time and cost. As broadband Internet connections become commonplace, more workers have adequate bandwidth at home to use these tools to link their home to their corporate intranet and internal communication networks.

Crowdsourcing The Internet provides a particularly good venue for crowdsourcing, because individuals tend to be more open in web-based projects where they are not being physically judged or scrutinized and thus can feel more comfortable sharing. Collaborative publishing Wikis have also been used in the academic community for sharing and dissemination of information across institutional and international boundaries. In those settings, they have been found useful for collaboration on grant writing, strategic planning, departmental documentation, and committee work. The United States Patent and Trademark Office uses a wiki to allow the public to collaborate on finding prior art relevant to examination of pending patent applications. Queens, New York has used a wiki to allow citizens to collaborate on the design and planning of a local park. The English Wikipedia has the largest user base among wikis on the World Wide Web and ranks in the top 10 among all Web sites in terms of traffic. Terminologies: AVI - (Audio Video Interleaved) A Microsoft Corporation multimedia video format. It uses waveform audio and digital video frames (bitmaps) to compress animation. Bandwidth - The capacity of an electronic line, such as a communications network or computer channel, to transmit bits per second (bps). Bitmap - A representation, consisting of rows and columns of dots, of a graphics image in computer memory. The value of each dot (whether it is filled in or not) is stored in one or more bits of data. For simple monochrome images, one bit is sufficient to represent each dot, but for colors and shades of gray, each dot requires more than one bit of data.

Bits and bytes Bit stands for binary digit: 0 or 1 A byte is made up of 8 bits It takes 1 byte to store one ASCII character ASCII stands for the American Standard Code for Information Interchange The combination of bits (which makes up one byte) below represents the letters below A 0100 0001 B 0100 0010 C 0100 0011 K stands for kilo and = 1024 (2 to the tenth power) M stands for mega. A MB, megabyte is about a million bytes (1024x1024) G stands for giga. A GB, gigabyte is about a billion bytes (1024x1024x1024) T stands for tera. A TB, terabyte is about a trillion! RAM is usually measured in MB Hard disk spaces is usually measured in gigabytes Blog - A blog is information that is instantly published to a Web site. Blog scripting allows someone to automatically post information to a Web site. The information first goes to a blogger Web site. Then the information is automatically inserted into a template tailored for your Web site. Bookmark - a way of storing your favorite sites on the Internet. Browsers like Netscape or Internet Explorer let you to categorize your bookmarks into folders. Boolean logic - a type of logic (using AND, OR, NOT operators, for example) used by search engines to find information on the Internet and in electronic databases. (For example, to find computer viruses instead of human viruses, you might try the keywords "computers and viruses.") Browser - A software program that allows users to access the Internet. Examples: Nona user interface for computers which allows you to read plain graphical text, not pictures, sound, or video, on the Internet. It is strictly text based, non-Windows, and does not place high memory

demands on your computer. An example is lynx .(http://lynx.browser.org/) Graphical a user interface for computers which enables people to see color, graphics, and hear sound and see video, available on Internet sites. These features are usually designated by underlined text, a change of color, or other distinguishing feature; sometimes the link is not obvious, for example, a picture with no designated characteristic. Examples are Netscape and Internet Explorer. CGI (Common Gateway Interface script) - a specificiation for transferring information between a Web server and a CGI program, designed to receive and and return data. The script can use a variety of languages such as C, Perl, Java, or Visual Basic. Many html pages that contain forms use a cgi program to process the data submitted by users/clients. Chat - real-time, synchronous, text-based communication via computer. Cookie - Information (in this case URLs, Web addresses) created by a Web server and stored on a user's computer. This information lets Web sites the user visits to keep of a user's browsing pattterns and preferences. People can set up their browsers to accept or not accept cookies. Cyberculture - "a collection of cultures and cultural products that exist on and/or are made possible by the Internet, along with the stories told about these cultures and cultural products." David Silver, "Introducing Cyberculture," Resource Center for Cyberculture Studies: http://www.com.washington.edu/rccs/ [last accessed11/24/2001]. Digit - A single character in a numbering system. In decimal, digits are 0 through 9. In binary, digits are 0 and 1. The os and 1s equate to "on and off functions. Digitization allows for perfect copying. When text, music, voice and video are in digitized, they can be electronically manipulated, preserved and regenerated without degredation of quality at high speed. Each copy of a computer file is exactly the same as the original. See more comprehensive definitions. Domain Name - A method of identifying computer addresses. Your e-mail address has a domain address. If you have an "edu" at the end of your e-mail address that means your account is affiliated with an educational institution. A "com" extension means you have a business account. A government account has a .gov suffix. dpi - (dots per inch) the way the resolution of display and printing is measured.

FAQs - Frequently Asked Questions. A list of questions and answers to explain products and troubleshoot problems. Firewall - The name "firewall" derives from the term for a barrier that prevents fires from spreading. A computer "firewall" is a barrier between your computer and the outside world. Just like a fire is most likely to spread through open doors in a building, your computer is most vulnerable at its ports (the doors). Without ports you could not go on the Internet or let Internet traffic enter your computer. An effective software firewall isolates your computer from the Internet using a code that sets up a blockade to inspect each packet of data, from or to your computer — to determine whether it should be allowed to pass or be blocked. Firewall software operates in various ways: Packet filters block traffic from IP addresses and/or port numbers. Proxy servers can break the connection between two networks. NATs (Network Address Translators) hides the IP addresses of client stations by presenting one IP address to the "outside" world. Stateful inspection verifies inbound and outbound traffic to be sure the destination and the source are correct. Firewall software can allow your computer to operate in stealth mode, so that its IP address is not visible. Flash - Animation software used to develop interactive graphics for Web sites as well as desktop presentations and games (Windows and Mac) by the company Macromedia. Flash on the Web is displayed by a browser plug-in. Non-Web presentations are run by a Flash player, included on a floppy or CDROM. Flashcan be used to create vector-based graphics in one or more timelines that provide a sequential path for actions. FTP - Using file transfer protocol software to receive from upload) or send to (download) files (text, pictures, spreadsheets, etc.) from one computer/server to another. .gif - (graphic interchange format) the usual format for a graphic that is not a photo. Animated gif files are embedded with coding that creates movement when the graphic is activated. See more graphics formats Home page - Generally the first page retrieved when accessing a Web site. Usually a "home" page acts as the starting point for a user to access information on the site. The "home" page usually has some type of table of contents for the rest of the site information or other materials. When creating Web pages, the "home" page has the filename "index.html," which is the default name. The "index" page automatically opens up as the "home" page.

HTML - A type of text code in Hypertext Markup Language which, when embedded in a document, allows that document to be read and distributed across the Internet. HTTP - The hypertext transfer protocol (http) that enables html documents to be read on the Internet. Hypertext - Text that is non-sequential, produced by writing in HTML (Hypertext Markup Language) language. This HTML coding allows the information (text, graphics, sound, video) to be accessed using HTTP (Hypertext Transfer Protocol). Hyperlink - Text, images, graphics that, when clicked with a mouse (or activated by keystrokes) will connect the user to a new Web site. The link is usually obvious, such as underlined text or a "button" of some type, but not always. Instant Messaging (IM) - a text-based computer conference over the Internet between two or more people who must be online at the same time. When you send an IM the receiver is instantly notified that she/he has a message. Interlaced - A graphics formatting technique that causes an image to gradually appear on your screen instead of appearing all at once. The image appears blurry at first and is replaced by successive waves of bit streams that gradually fill in the missing lines until the image fully appears in full resolution. This gradually rendering of the image is helpful for Web users who have slow modems and connections, since this technique allows the viewer to see enough of the image to decide whether or not to continue loading it. For fast connections, there is no discernible difference. Internet - A global network of thousands of computer networks linked by data lines and wireless systems. [Background history on the Internet -The Internet, originally the ARPAnet (Advanced Research Projects Agency network), began as a military computer network in 1969. Other government agencies and universities created internal networks based on the ARPAnet model. The catalyst for the Internet today was provided by the National Science Foundation (NSF). Rather than have a physical communications connection from each institution to a supercomputing center, the NSF began a "chain" of connections in which institutions would be connected to their "neighbor" computing centers, which all tied into central supercomputing centers. This beginning expanded to a global network of computer networks, which allows computers all over the world to communicate with one another and share information stored at various computer "servers," either on a local computer or a computer located anywhere in the world. The Internet is not governed by any official body, but

there are organizations which work to make the Internet more accessible and useful.] IP Address - (Internet Protocol) The number or name of the computer from which you send and receive information on the Internet. JAVA - a computer language, developed by Sun Microsystems, that lets you encode applications, such as animated objects or computer programs, on the Internet Javascript - A Web scripting language developed by Netscape. It was developed independently of the full JAVA language and is an "open" language, free for anyone to use and adapt. For example, The Java Script Source has many scripts people can adapt for their own purposes. .jpg (or jpeg)- (joint photographic expert group) a file format for photographs on Web pages. The "jpg" format compresses large photo files so they don't take up as many kilobytes of memory. See more graphics formats Listserv - An e-mail list of e-mail addresses of people with common interests. Software enables people who belong to a list to send messages to the group without typing a series of addresses into the message header. Usually members of the group in the listserv have to subscribe to the mailing list. Modem - A device that connects your computer to the Internet, when you are not connected via a LAN (local area network, such as at work or on a campus.) Most people connect to a modem when using a home computer. The modem translates computer signals to analog signals which are sent via phone lines. The telephone "speaks" to the computer/server which provides your Internet access. MPEG - (Short for: Moving Picture Experts Group) MPEG-1

MPEG-2

Format for compressing video with audio for playback from storage media with low data transfer rates such as CDROMs or over the network at VHS quality. Format for compressing video with audio at broadcast quality resolution for playback in higher data transfer rate environments. Usually used for real-time encoding in the professional market, satellite digital television (DirecTV, USSB), and for DVDs and other types of video CDs.

MP3 MPEG Layer 3

Format for compressing audio only defined in both MPEG-1 and MPEG-2. Commonly used for digital music played on personal computers (MP3 songs) but also targeted at applications such as digital phones and new hardware MP3 players intended as discman or car CD player replacements.

Multimedia - The Web's integration of audio, video, graphics and text. Newsgroup - An Internet "site" centered around a specific topic or course. Some newsreader software can "thread" discussion so there can be various topics centered around a central theme. An advantage over e-mail is that the messages are archived and don't reside in your e-mail account, taking up your memory, unless you set up a "sent mail" or "carbon copy" option. The messages can often be threaded according to a particular discussion. PHP - (Hypertext Preprocessor) open source, server-side HTML scripting languaage used to create dynamic Web pages. PHP is embedded within tags, so the author authorr can move between HTML and PHP instead of using large amounts of code. Because PHP is executed on the server, the viewer cannot see the code. PHP can perform the same tasks as a CGI program can do and is compatible with many different kinds of databases. Portal - A Web site "gateway" that provides multiple services, which could include Web searching capability, news, free-email, discussion groups, online shopping, references and other services. A more recent trend is to use the same term for sites that offer services to customers of particular industries, such as a Web-based bank "portal," on which customers can access their checking, savings and investment accounts. RSS - (Rich Site Summary or RDF [Resource Description Framework] Site Summary). An XML format for sharing content among different Web sites such as news items. How does it work? A Web site can allow other sites to publish some of its content by creating an RSS document and registers the document with an RSS publisher. A web publisher can post a link to the rss feed so users can read the distributed content on his/her site. Syndicated contentcan can include news feeds, listings of events, stories, headlines, etc. Search Engine - specialized software, such as AltaVista and Yahoo, that lets WWW browser users search for information on the Web by using keywords, phrases, and boolean logic. Different search engines have different ways of categorizing and indexing information. Search engines are accessed by typing in the URL of that engine or using a browser's compilation of search engines in its Internet search function.

Shockwave - A three dimensional (3D) animation technology/format creataed by the Macromedia company. Macromedia Director producess Shockwave files, which can be viewed through a Shockwave player, a browser"plug-in" computer program or other multimedia applications that access the player. Shockwave can be used to create more sophisticated animations than the Macromedia Flash format. Shockwave uses the .dir file extension for source files and .dcr extension for Shockwave "movies." Telnet - The command to log on to another computer on the Internet. URL - A universal resource locator (a computer address) that identifies the location and type of resource on the Web. A URL generally starts with "http." Vector - A line in computer graphics designated by its end points (x-y or x-y-z coordinates). A vector layer does not use pixels for storing image information. Instead, it stores a vector object as a set of properties that describe its attributes, dimensions, and position in the image. Each time an image is opened, these properties are used as instructions for drawing the objects. Because the objects are independent elements, you can move them without affecting the rest of the image. Virtual Community - a term commonly used to describe a group of people who exchange ideas through computer networks, listservs, newsgroups, and Webbased bulletin boards. They might not ever meet face-to-face. Generally these people meet over the long-term, on a regular basis, and share their ideas about a variety of subjects, depending upon their special interest. The discussions could relate to hobbies, music, health, self help issues, and professional and scholarly activities. Virus - a computer program usually hidden in an existing program. Once the existing program is executed, the virus program is activated and can attach itself to other programs or files. Viruses can range from benign activities such as attaching a harmless message to performing malicious activities such as destroying all the data on a computer hard drive. Viruses are commonly distributed as e-mail attachments which activate when the attachment is opened. Virus protection software, updated regularly with the latest virus definitions, can help protect computers from viruses. Web Bot - A term that applies to programs/applets (macros and intelligent agents) used on the Internet. Such bots perform a repetitive function, such as posting messages to multiple newsgroups or doing searches for information. Wide World Web (WWW) - A hypermedia information storage system which links computer-based resources around the world. Computer programs called Browsers enable words or icons called hyperlinks to display, text, video, graphics and sound on a computer screen. The source of the material is at a

different location - a different file in the same directory, a file in another computer, which can be located anywhere in the world. For example www.moyomedia.co.tz WORM - A destructive computer program that replicates itself throughout your computer's hard drive and and memory. Worms use up the computers resources and pull the system down. Worms can be spread in mass-e-mailing if the user opens an attachment. (2) A program that moves through a network and deposits information at each node for diagnostic purposes or causes idle computers to share some of the processing workload. XML (Extensible Markup Language) - is a less robust variety of SGML, a system for organizing and tagging elements of a document so that the document can be transmitted and interpreted between applications and organizations. Human readable XML tags defines "what it is," and HTML defines "how it looks." XML allows designers to create their own tags. For example: HTML Jane Doe March 27, 1975 XML Jane Doe 03-27-75 In the HTML version the tags identify formatting options, such as font size and bold. In the XML example, the tags identify the content. Because XML can support business-to-business transactions by making the transmission and interpretation of data easier, it has the potential to become the standard for the exchange of data over the Internet.