Meta Search Engine
 

A metasearch engine is a search tool that sends user requests to several other search engines and/or databases and aggregates the results into a single list or displays them according to their source. Metasearch engines enable users to enter search criteria once and access several search engines simultaneously. Metasearch engines operate on the premise that the Web is too large for any one search engine to index it all and that more comprehensive search results can be obtained by combining the results from several search engines. This also may save the user from having to use multiple search engines separately.

For keyword searching google keyword tool or word-tracker is best.

nice information thanks.....

Meta search engine doesn't have its own database and they search the database of real search engine usually many search engine at the same time and provide results.

Thanks for sharing.... nice piece of info ...