INTERNET

The global computer network connecting computers by telephone cables, optical fibers, and microwaves is called the Internet. The Internet provides almost instant electronic communication around the world.

HOW DOES THE INTERNET WORK?

Every computer linked to the Internet has an address. This is its IP number. When you send a message or request information on the Internet, your computer sends packets of data with the sender’s and receiver’s addresses attached. Special computers called servers and routers direct the data through the Internet.

WHAT IS THE WORLD WIDE WEB?

The World Wide Web is a library of billions of pages of information, including SEARCH ENGINES, stored on servers connected to the Internet. The pages are written using hypertext, which links them. A program called a browser on your computer uses a web address (URL) to request a page. The request is routed through the Internet to the correct server, and the page is sent back to your computer.

WHAT IS HYPERTEXT?

Web pages are written using hypertext. Hypertext links one web page to another. Web pages contain text prepared in a computer language called HTML. Hypertext links special words or phrases to other sections of the document, or to other documents. Clicking on a link takes you to the linked page.

BIOGRAPHY: TIM BERNERS LEE British, 1955- MARC ANDREESSEN American, 1971-

Tim Berners Lee invented the World Wide Web as a source of information for scientists in the 1980s. In 1993, Marc Andreessen developed the first browser program (Mosaic) with text, pictures, and hypertext links.

SEARCH ENGINES

If you need to find information on the World Wide Web, you use a program called a search engine. When you enter keywords, the search engine (located on a server) makes a hypertext list of Web pages that have the words you are looking for.

HOW DOES A SEARCH ENGINE RANK PAGES?

Entering the words “team sports” will produce a list of millions of results from a search engine. The engine tries to place the most relevant pages at the top of the list. Different engines do this in different ways. For example, the engine may check if all the words appear or how many times they appear.

Copyright © 2007 Dorling Kindersley