Anna Patterson explains the problems of search engine design in practical terms in this lengthy article.

Natural-language answer engine, which queries the internet in real time, and will serve up full text from selected sites.

The U.S. Government's official search engine. Find information from federal, state, local, tribal and territorial governments. Meta-search special government databases.

A cross between a search engine and an encyclopedia. The results return complete, informative sentences about the search topic. Related topics are suggested.

A straightforward search engine with a simple interface.

Offers the option to specify a general topic as well as specific keywords for more precise results.

In a five-part series, NPR's Rick Karr takes a look at the business of search engines.

Search engine with a simple interface and no advertising. Offers the ability to create a customized topical or personal search index.

A clustering engine with a streamlined interface, which presents all results in one column and clusters by topic in another.

Microsoft provides search of the web, news, images and its own encyclopedia, Encarta. Also offers desktop search via a toolbar.