|
| |
|
What
is Search Engine? |
|
A program that searches documents for specified keywords and
returns a list of the documents where the keywords were found. Although
search engine is really a general class of programs, the term is often used
to specifically describe systems like Alta Vista and Excite that enable
users to search for documents on the World Wide Web and USENET newsgroups. |
|
|
|
|
|
|
|
Typically, a search engine works by
sending out a spider 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 search engine is an information 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. This list is often sorted with respect to
some measure of relevance of the results. Search engines use regularly
updated indexes to operate quickly and efficiently. |
|
|
|
|
|
|
Without further qualification, search engine
usually refers to a Web search engine, which searches for information on the
public Web. Other kinds of search engine are enterprise search engines,
which search on intranets, personal search engines, and mobile search
engines. Different selection and relevance criteria may apply in different
environments, or for different uses.
Some search engines also mine data available in newsgroups, databases, or
open directories. Unlike Web directories, which are maintained by human
editors, search engines operate algorithmically or are a mixture of
algorthmic and human input. |
|
