Common Terminology of WWW

• Website: Website is the location of web pages created by any Organization, Universities and Government agencies to provide information regarding themselves like www.ekantipur.com. Each and every websites has its own address, is known as Internet address. After connecting to the internet, we have to search any information by using related website address.

• web Page: Web page is the collection of information that is stored in the website. The www consists of a huge collection of documents with related website called called Web Page. Web Page provides vast amount of information of related websites.

• Browser: Browser is a client server that allows a user to display and interact with a hypertext documents.

• Web Server: A computer that is maintained by a system administrator or Internet Service Provider (ISP) and that responds to request form a user's browser. A web server is a site on which the web page are kept. It is a program that responds to requests from web browsers to retrieve resources.

• Home Rage: The Home Page is the first hypertext document regarding the web address displayed when a user connects to any web server.

• Hypertext Markup Language (HTML): HTML is the encoding scheme used to create a web document.

• Hypertext Transfer Protocol (HTTP): HTTP is a protocol used on the web to transfer hypertext document. A protocol is a set of rules used by the computers to communicate over the network.

• Uniform Resource Locator (URL): URL is the web-addressing scheme that spell our extra location of an internet resource.

• Graphic Interchange Format (GIF): GIF is the standard images format on the web. This format is used if the image is the line drawing; it is considered superior to the JPEG format for its clarity and ability to maintain the originality of an image without lowering its quality.

• JPEG or JPG: The Joint Photographic Expert Group (JPEG) format is used if the image is a photograph, a medical image or a complex photographic illustration. JPEG images are inherently full-color images, so they will look dis-stored when viewed on a monitor supporting 256 colors or less.

• PNG: The Portable Network Graphic (PNG) format is an alternative to GIF. The PNG format provides a portable, legally free, well-compressed, well-specified for bit mapped image files that retain their high resolution.

• Internet Service Provider (ISP): A company that provides individuals or companies access to the internet and the World Wide Web. When you sign a contract with an ISP, you are given a telephone number, a user name, password and other connecting information so you can connect your computer to the ISP's computers. An ISP typically charges a monthly and/or hourly connecting fees.

• Domain Name: Represent the name of a area of specific internet controlling by a company, government or organization. Example:- @ccsl.com.np, @cnet.wlink.com.np............. etc
• Router: A specialized machine that runs various protocols to direct network packets from one segment to another.

World Wide Web (www)

This internet application is drawing the attention of many peoples the World Wide Web(www). WWW is a series of servers which are interconnected from hypertext. It is a method of providing information in which certain text is highlighted items are known Hyperlinks. They allows us to navigate from a document to another through they may be situated on another servers. The user can use use a browser like Internet Explorer, Mosaic and Netscape Navigator to navigate the web. A browser is software that helps user to navigate the www.

Advantage of www.

1. A link in a web document can be used to open other documents.
2. Web pages can contain pictures, buttons and even links to sound files in addition to text, thus allowing multimedia application.
3. Sophisticated web document allow users to interact with application through dialogs boxes and forms.
   

Computer Virus

A program which is written to cause problem in the computer in known as computer virus. Due to virus data may be corrupted or lost. A virus is commonly transferred through computer to computer on floppy disk or over a telephone link. Virus can be stop by using special anti-virus software.
A program that attempts to spread from computer to computer and either cause damage or annoy users by printing messages or altering what is displayed on the screen. When a program is inserted into another program then it is known as a computer is attacked by virus. It replicates itself and spread to another computer through floppy, mail and shared media. When the user run the infected program then it get chance to replicates itself.
Computer virus does not allows computer to run smoothly. Frequently computer hangs. It can also infect disk by attaching themselves to special programs in area of your disk called boot records and master boot records. Due to the virus computer may not boot and the size of the files changed automatically. Some of the names of computer virus are: C-Brain, Macmag Stores, Cascade, Jerusalem, Internet, Patch COM, Bomb, Macro virus etc.

Hardware, System Software & Application Software

The hardware cannot do anything without the software control. A computer will run only if mechanisms are provided th handle files, launch programs and deals with other user requests. These functions are carried out by system software called operating system. It is executed ta startup time and run constantly while the computer is on. The operating system instructs the computer on how to operate properly and manages the To and For flow of data from each part of the computer. It tends to isolate the hardware from the user, An operating system helps people use computer in many ways. But the functions performed by an OS are generally transparant or invisible to the users, eg: MS-DOS, OS/2, Windows, (95/98/2000/xp), Linus, UNIX etc.

An operating system is the program that, after being initially loaded into the computer, controls the execution of computer program and which may provide scheduling, debugging, Input/Output control, compilation, storage supervision and management of data etc. The operating system provides many important function to the people using the computer. From the largest mainframes and super computers to the small personal computer almost all computer system run under OS control.

As computer conisists of various resourceslike memory, CPU, Disk etc. It is very difficult for the user of computer to understand how to operate them directly. So OS becomes the interpreter between the computer hardware and users. It interprets the command of user to the hardware. For example, if we want to save our Bio-data in floppy disk, then we don't know "how to wright" or "where to write" inside the floppy, but our duty is simply t o give command to the operating system and then it will be the job of OS to tell the floppy drive what to do exactly. In short, OS acts as a interface and hides every details of working principle of computer from the user.

Memory

Memory is the place where we can store or hold the data and instruction for further operation. Memory stores three basic items: The operating system and other system software that control the usage of the computer equipment and application programs designed to carry out a specific task such as word processing and the data being processed by application programs. It is the storage area where the data are stored temporarily or permanently as per the need. Basically we have two types of memory; internal memory is simply called main memory or primary memory and the external memory called secondary memory or auxiliary memory or backup storage devices.

• Primary memory (Main memory)

Primary memory is the working space for the computer's processor. It is an area where the program and data being operated on by the processor must reside. It is used when small amount of data have to be exchanged quickly and used repeatedly. It allows CPU to store and retrieve data quickly.

• Secondary memory (Auxiliary storage or Secondary storage)

It is non-volatile memory that is stored externally to the computer. It is usually used for the storage of large amounts of data for permanent or long term storage of data or programs. Though, the secondary storage can hold much more data than primary storage, access to the data is slower. Only the programs and data currently needed by the processor reside in main memory. Normally, all other information is stored in secondary storage and is transferred to main memory when needed.

Levels of Hardware

1. Machine Level: Several hardware levels are presented in machine level. These are the basic elements of computer. They are processer, input/output, main device, axuiliary storage etc. This is top level of hardware in the hardware hierarchy where user can interact with them directly.
2. Micro Progaram Level: A sequence of microinstruction constitutes the micro program. The micro program is permanently stored in Read Only Memory(ROM) and normally cannot be changed. The Program in the permanent storage is called firmwarm. micro program are written for the control unit of the modern microprocesser. each computer instruction as actually accomplished by the execution of the related micro instruction in the micro program level.
3. Digital Logic Level: Almost all basic operation of the machine are provided at this level. The basic element at this level can store, manipulate and transmit data in the form of simple binary representations. These digital logic elements are called gates. A gates is normally constricted from small number of transistors and other electronic components. Many gates are combined together to form computer subsystems like adder, subtracter, multiplexer, decoder etc in a simple IC form or in multiple IC form. The standard digital logic devices are combined together to form computer processer or computer memories.
4. Electrical and Electronic Component Level: Almost all modern computer devices are built from simple electronic components such as diode, transistors, capacitors, registor or other components in integratedcircuits (IC) form. These components rely on suitable power supplies and operating environment.

Networking and Its Types

Networking is a collection and rearrangement of intelligent and distributed machine that shares data and information through lines of communication. It is very important concept to communicate from one place to another place. It is also defined as the connection of computer's pheripheral devices with cables oe even without cables (communication madia).
Types of Networking

1. LAN (Local Area Networking): This is the networking within a very limited area like a single building, within a college. LAN refers to a combination of hardware and transmission media. If computers are connected near to ech otherwith a communication media is called LAN. Due to the use of one kind of cable i.e. communication media, this is comparatively faster. It is limited generally upto 2 KM. The most important components in LAN are File server and OS (operating system).

2. MAN (Metropolitan Area Networking): When LAN grows and spread in area then it becomes MAN. It is also extended upto a city or a large geographical area. It comprises a combination of different hardware and transmission media. They are slower than LAN. The two important components of MANs are Security and Standarization.

3. WAN (Wide Area Networking): A wide area network is simple as LAN & MANs. WANs connect LANs that may be an opposite side of building, across the country of around the world. WANs can be characterized as either enterprises oe Global WANs. An enterprise WAN connects ars entire organization including all LANs at various site. Where as Global WANs also span the world but they do not have to connect LANs with in a single organization. The internet is an example of Global WAN.