Each individual search engine covers only about 4 to 20 percent of the Web. MetaSearch engines can provide more extensive coverage by searching simultaneously in several of the largest search engines' databases. MetaSearch engines are useful for a quick overview on what is available on the Web on a particular subject. The following are addresses of some efficient multi-threaded search engines:

Searches for your query in Alta Vista, Excite, HotBot, Infoseek, Lycos, WebCrawler, and Yahoo. It then ranks the results by relevance indicating which search engine retrieved them. Debriefing also eliminates duplicate results from different search engines.

Looks for results in 25 search engines, then displays them by search engines, from most specific to most general result.

Uses up to nine search engines and allows you to select the ones you want to be searched.

You can type a question and Jeeves will try to provide you the answer by looking in several search engines. It will group the results by engine as well as by the sites who seem to provide answers closer to your question.