Search Engine

The Internet provides access to a wealth of information on countless topics contributed by people throughout the world .However, the internet is not a library in which all its available items are identified and can be retrieved by a single catalogue . In fact , no one knows how many individual files (could be billions ) reside on the Internet. Hence , to conduct a search on the Internet , a special search tool , known as ' search engines ' are used.A search engine is a searchable database of internet files collected by a computer program called a wanderer , crawler , or spider . It allows the user to enter keywords relating to particular topics and retrieve information about Internet sited containing those keywords . As such , a search engine consists of four components :

1.Spider : Program that traverses the web from link to link , identifying and reading pages.
2.Indexing Software : Program that analyses web a pages that are downloaded by spiders.
3.Database : Warehouse of the web pages downloaded and processed.
4.Search Engine Mechanism : Software that enables users to query the index and that usually returns results in term relevancy ranked order.

A search engine doesn't really search the web directly.To find the information on the millions of web pages , a search engine employs special software , called spiders. After spiders find pages , they pass them on to another computer program for indexing . This program identifies the text , links , and other content in the page and stores if in the search engine database's files so that the database can be searched by keyword. Note that creating index and updating search database is a never-ending process because of the constantly changing nature of the web . As a result , the spiders are always 'crawling'.




One of the famous search engine is GOOGLE search engine

When users search the web using a search engine , they are provided with the links of all the searched web pages. On clicking on the links provided in a search engine's search results , the correct versions of the web pages are retrieved form the server.