Metasearch engine
Encyclopedia
A metasearch engine is a search
tool that sends user requests to several other search engines and/or databases and aggregates the results into a single list or displays them according to their source. Metasearch engines enable users to enter search criteria once and access several search engines simultaneously. Metasearch engines operate on the premise that the Web
is too large for any one search engine to index it all and that more comprehensive search results can be obtained by combining the results from several search engines. This also may save the user from having to use multiple search engines separately.
The term "metasearch" is frequently used to classify a set of commercial search engines, see the list of search engines, but is also used to describe the paradigm of searching multiple data sources in real time. The National Information Standards Organization (NISO
) uses the terms Federated Search
and Metasearch interchangeably to describe this web search paradigm.
Metasearch engines create what is known as a virtual database. They do not compile a physical database
or catalogue of the web. Instead, they take a user's request, pass it to several other heterogeneous databases and then compile the results in a homogeneous manner based on a specific algorithm
.
No two metasearch engines are alike. Some search only the most popular search engines while others also search lesser-known engines, newsgroup
s, and other databases. They also differ in how the results are presented and the quantity of engines that are used. Some will list results according to search engine or database. Others return results according to relevance, often concealing which search engine
returned which results. This benefits the user by eliminating duplicate hits and grouping the most relevant ones at the top of the list.
Search engines frequently have different ways they expect requests submitted. For example, some search engines allow the usage of the word "AND" while others require "+" and others require only a space to combine words. The better metasearch engines try to synthesize requests appropriately when submitting them.
Information retrieval
Information retrieval is the area of study concerned with searching for documents, for information within documents, and for metadata about documents, as well as that of searching structured storage, relational databases, and the World Wide Web...
tool that sends user requests to several other search engines and/or databases and aggregates the results into a single list or displays them according to their source. Metasearch engines enable users to enter search criteria once and access several search engines simultaneously. Metasearch engines operate on the premise that the Web
World Wide Web
The World Wide Web is a system of interlinked hypertext documents accessed via the Internet...
is too large for any one search engine to index it all and that more comprehensive search results can be obtained by combining the results from several search engines. This also may save the user from having to use multiple search engines separately.
The term "metasearch" is frequently used to classify a set of commercial search engines, see the list of search engines, but is also used to describe the paradigm of searching multiple data sources in real time. The National Information Standards Organization (NISO
Niso
Niso is a genus of very small parasitic sea snails, marine gastropod mollusks or micromollusks in the family Eulimidae. -Species:According to the World Register of Marine Species the following species with accepted names are included within the genus Niso * Niso aeglees Bush, 1885* Niso albida...
) uses the terms Federated Search
Federated search
Federated search is an information retrieval technology that allows the simultaneous search of multiple searchable resources. A user makes a single query request which is distributed to the search engines participating in the federation...
and Metasearch interchangeably to describe this web search paradigm.
Operation
Database
A database is an organized collection of data for one or more purposes, usually in digital form. The data are typically organized to model relevant aspects of reality , in a way that supports processes requiring this information...
or catalogue of the web. Instead, they take a user's request, pass it to several other heterogeneous databases and then compile the results in a homogeneous manner based on a specific algorithm
Algorithm
In mathematics and computer science, an algorithm is an effective method expressed as a finite list of well-defined instructions for calculating a function. Algorithms are used for calculation, data processing, and automated reasoning...
.
No two metasearch engines are alike. Some search only the most popular search engines while others also search lesser-known engines, newsgroup
Newsgroup
A usenet newsgroup is a repository usually within the Usenet system, for messages posted from many users in different locations. The term may be confusing to some, because it is usually a discussion group. Newsgroups are technically distinct from, but functionally similar to, discussion forums on...
s, and other databases. They also differ in how the results are presented and the quantity of engines that are used. Some will list results according to search engine or database. Others return results according to relevance, often concealing which search engine
Search engine
A search engine is an information retrieval system designed to help find information stored on a computer system. The search results are usually presented in a list and are commonly called hits. Search engines help to minimize the time required to find information and the amount of information...
returned which results. This benefits the user by eliminating duplicate hits and grouping the most relevant ones at the top of the list.
Search engines frequently have different ways they expect requests submitted. For example, some search engines allow the usage of the word "AND" while others require "+" and others require only a space to combine words. The better metasearch engines try to synthesize requests appropriately when submitting them.
See also
- For engines, see the list of search engines
- Search aggregatorSearch aggregatorA search aggregator is a type of metasearch engine which gathers results from multiple search engines simultaneously through RSS search results...
- Federated searchFederated searchFederated search is an information retrieval technology that allows the simultaneous search of multiple searchable resources. A user makes a single query request which is distributed to the search engines participating in the federation...
- MetabrowsingMetabrowsingWith the popularization of the Internet in the late 1990s, different approaches to browsing Web-based information emerged as alternatives to the standard Web browser. According to LexisNexis the term "metabrowsing" began popping up in mainstream media in March 2000...
- MultisearchMultisearchMultisearch is a multitasking search engine which includes both search engine and metasearch engine characteristics with additional capability of retrieval of search result sets that were previously classified by users...
- Travel websiteTravel websiteA travel website is a website on the world wide web, that is dedicated to travel. The site may be focused on travel reviews, the booking of travel, or a combination of both. Approximately seventy million consumers researched travel plans online in July 2006...
- Search aggregator
External links
- Guide to Meta-Search Engines by UC Berkeley libraries with recommendation not to use them for serious research.
- Meta-search: More heads better than one? Argument against Berkeley's negative recommendation