Every search engine in the internet must have at least one web crawler. The other names of web crawler are web spider and bot. The main task of a web crawler is to crawl every web pages fed to it. It will retrieve the contents of web pages crawled, and parse it to get the data and hyperlinks. It then continues to crawl the found hyperlinks. The parser sends data to the indexer and saves it into the database. A search into a search engine actually does not search into the real web site, but it searches the search engine database. The output of search engines is a list of snapshots of web pages with its hyperlinks. The user should open web pages he needs by clicking the hyperlinks.