Search engines are tools that help you find what you want on the Web. They use algorithms (often called spiders or crawlers) that are programs used to compile a database of pages found on the publicly accessible Web.

When you enter a search, the search engine scans its own database to match your terms against terms in the pages of its database. So, each search engine searches the part of the Web it has collected - not the whole Web, but a large portion of it - and each has a somewhat different database which is why results can vary between each one.

Google has the largest database of any search engine, but some others you might try are Ask.com and Yahoo!.