What is meant by Networking?


When two or more computers communicate directly or exchange information, it is called computer networking. In its early days, computers, even large ones, were isolated- they could be used only by one individual or one organisation. There was no link between one computer and another. 

With improvement in technology, it has become possible to link together several computers, and a user on one system could use facilities on other systems in the network. The area covered by a network now ranges from a university campus to several continents.
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What is Data Transmission?


 

When data has to be transmitted electronically, data communications channels are used. These channels can be roughly divided into three categories:
1.      Narrowband
2.      Voiceband; and
3.      Broadband.
The names reflect the capacity of the channels for transmitting data. The unit of measure used is bits per second or characters per second; one character is normally equivalent to 8 bits.
A narrowband channel can transmit data at the rate of about 10 cps. A telegraph line is an example of a narrowband channel. Since no typist can type more than 10cps, this line is sufficient for data being transmitted directly.
A voiceband channel can transmit data at a maximum rate of about 8000 cps. The telephone lines fall into this category. By far, this is the most widely used method of data transmission.
A broadband channel can transmit data at the rate of millions of character per second. A television cable which can transmit data at the rate of millions of characters per second. A television cable which can transmit 10 million cps is an example. TV cables are also known as coaxial cables. Satellites and microwave radio also provide broadband capacity.
The best high capacity transmission channel is made possible by the use of optical fibres. In this technology, semiconductor lasers transmit data in the form of light along hair thin glass fibres at the speed of light. Because the fibres are extremely thin, thousands of fibres can be included in a single cable making large volumes of data transmission possible.

What is E mail?


The domain name which comes after the symbol@, may also include an extension other than .com which stands for commercial business. It may be on educational institution ‘edu’, on organisation ‘org’ or government departments ‘gov’. Domains are classified as non geographics and geographic, countires have fixed domain names: eg. the domain name of the UK is .uk and that of India is .in. There may be sub domains that correspond to organisations such as NASA.

World Wide Web


World Wide Web (invented by Tim Berners Lee), which allows a point and click navigation without the help of formidable computer commands. Then came Marc Anderson who wrote a program, Mosaic, to add colourful pictures, sound and video to the web. The web is the most impressive internet application. It uses a concept called hypertext, displaying text and images in relation to each other on a web page where individual words or pictures act as electronic links to other (related) documents.
A simple mouse click on a word can take the user to that word’s definition, an illustration, or another related web page. The web documents are written in a computer language called hypertext mark up language (HTML) and transferred by a protocol called hypertext transfer protocol (HTTP). The web pages are identified by unique uniform resource locators (URLs).
The web would have been very difficult to operate but for the hypertext concept. Now one simply types the URL of the page one wants to visit. The computer then displays the page which is an HTML documents with texts, pictures, sounds etc. As the user reads the page, certain words can act as hyperlinks pointers to the URL of other web pages with related information.

GIF versus JPEG


GIF versus JPEG: GIF stands for Graphics Interchange Format. It is the only format that all graphics-savvy browsers can display, so it is the format to be used for graphics that is to be seen by everyone. The bad part about GIF graphics is that they are limited to 256 colors and typically do not compress as well as JPEG graphics do. The latest version of the GIF specification ( version 89a) supports transparent mode, a nifty rectangles. To make a GIF’s background colour transparent, one end up with a GIF that looks like an irregularly shaped object.

The easy rule to remember
1. Use GIF format with graphics that you have created on your computer such as horizontal rules, buttons, or animation.
2. Use JPEG format when the images are scanned pictures or photographs.
GIF file can contain the maximum of 256 colors (8 bit) or less, which is good for customizing your graphic files. For example, if you create a GIF image of a red arrow, , you can customize the file to have only two colors, read and white. This means that the file is very very small because its palette contains only two colors. GIF file will yield a higher quality and smaller size image, compared to JPEG, when it is used with computer generated graphics such as icons, logos, buttons, etc.
JPEG was built to contain 24-bit (16.7+ million colors) and was developed specifically for photographic-style images. JPEG stores the information of images by keeping track of color changes. The advantage of JPEG is that it can carry a smaller file size than GIF when used in storing photographs and images with a wide variety of shading. But, it will not yield a smaller file when dealing with low color level and details like computer generated graphics.
GIFs also has some special features such as animation, transparency, and interlacing.

What is GIFF?


Some browsers display interlaced GIFs as they read them, first they display every eight line, then fourth line, then every second line and then every line. This display method makes people, waiting for the image to load, to quickly figure out what the final image would look like.
Other browsers bring in a rough version of the graphic and gradually refine it. GIFs also support animation. It is possible to piece together numerous GIFs and create a simple movie.