A search engine or search service is a document retrieval system designed to help find information stored on a computer system, such as on the World Wide Web, inside a corporate or proprietary network, or in a personal computer. The search engine allows one to ask for content meeting specific criteria (typically those containing a given word or phrase) and retrieves a list of items that match those criteria. Search engines use regularly updated indexes to operate quickly and efficiently.
Further details can be found at:
<http://en.wikipedia.org/wiki/Search_engine>
The key variants of search engines will be discussed at the following pages: