Search Engines
Search engines are online tools designed to search for information on the World Wide Web. This information includes many forms of media: text, graphics, videos, images, etc. Search engines are basically large databases.
The three most popular search engines are Google, Yahoo, and Microsoft Bing Search.
Google is an enormous "spider" that keeps searching the web and indexing billions of URLs. Google uses advanced algorithm that ranks web pages. Web sites' Page Rank is based on the ranking of pages that link to the web page.
A spider is an automated piece of software that "crawls" the Web looking for information.
Yahoo has created its own search technology. This technology is based on the combined technology of Inktomi search engine, Overture search engine, AlltheWeb search engine, and AltaVista search engine that Yahoo acquired.
Microsoft has created it own search technology, powered by web crawlers called msnbot.
