In the internet information retrieval system that designed to help find information stored,a such as on the WWW or in other proprietary network is widely known as Search Engine. Specific criteria are needed (word or phrase ) to retrieves a list of items that match those criteria.
Search engine usually refers to a Web search engine,which searches for information on the public Web. With further qualification,other kinds of search engine are enterprise search engines,which search on intranet,personal search engine,and mobile search engine ( 1 ).
There are three basic tasks of search engine (2):
* They search the Internet —or select pieces of the Internet —based on important words.
* They keep an index of the words they find,and where they find them.
* They allow users to look for words or combinations of words found in that index.
A search engine operates,in the following order:
1. Web Crawling