Typically, a search engine works by processing a user request such as a keyword or question. It sends out a
to fetch as many documents as possible. Another program, called an indexer
, then reads these documents and creates an index based on the words contained in each document.
Each search engine uses a proprietary algorithm to create its indices such that, ideally, only meaningful results are returned for each query.
A Web "supersite" that provides a variety of services including Web searching, news, white and yellow pages directories, free e-mail, discussion groups, online shopping and links to other sites. Web portals are the Web equivalent of the original online services such as CompuServe and AOL. Although the term was initially used to refer to general-purpose sites, it is increasingly being used to refer to vertical market sites that offer the same services, but only to a particular industry such as banking, insurance or computers.: