Information retrieval is the location of documents or information within a document. Such retrieval can be accomplished by physically finding a book or other volume in a library. With the creation and expansion of the Internet, electronic retrieval of information has become an important and ubiquitous means of obtaining information.

Electronic information retrieval utilizes the use of directories or search engines. Directory search programs, called a robot, spider, or wanderer, such as Altavista and Lycos, search for URLs--universal resource locators--which are global addresses of documents on the World Wide Web. Search engines provide more control for the user in performing a search. Search engines such as Excite, Magellan, and Google respond to a query, a string of words (not necessarily English), which characterizes the information that the user seeks. These are programs that query, locate, and retrieve information in databases. Boolean searches focus on key words supplied by the user.

Some electronic information retrieval involves the use of electronic filters to rank the retrieved documents in terms of their perceived relevance to the user request. Also, user requested parameters could be weighed to permit a more fruitful search. For example, in the search request "use of computers for information retrieval," the words "use," "of," and "for" could be given little weight.

The goals of the search methods is to provide the user with the most precise or relevant documents in the midst of all the documents that might be located, or recalled, by the search criteria. The recall percentage can be very high. Ideally, the precision percentage should be much lower.

Because search engines have different criteria, it can be useful to use more than one search mechanism to gain information.