search engine is an information retrieval system designed to help find information stored on a computer system. Search results are usually presented in a list and are usually called hits . Search engines help minimize the time it takes to find information and the amount of information to be consulted, similar to other techniques for managing information overload.
The most common and searchable form of search engines is the Web search engine that searches for information on the World Wide Web.
Video Search engine (computing)
How search engines work
The search engine provides an interface for a bunch of items that allow the user to specify criteria about an item of interest and have the machine find matching items. These criteria are referred to as search queries. In the case of a text search engine, the search query is usually expressed as a set of words that identify the desired concept that may contain one or more documents. There are several search query syntax styles that vary in firmness. It can also rename it in the search engine from the previous site. While some text search engines require users to enter two or three words separated by spaces, other search engines can allow users to specify all documents, images, sounds and various natural language forms. Some search engines apply an increase to the search query to increase the likelihood of providing a set of quality items through a process known as query expansion. Query understanding methods can be used to standardize query languages.
The list of items that meet the criteria specified by the request is usually sorted, or ranked. Improving items by relevance (from highest to lowest) reduces the time it takes to find the desired information. The probabilistic search engine rates items based on the size of similarities (between each item and query, usually on a scale of 1 to 0, 1 most similar) and sometimes popularity or authority (see Bibliometrics) or using relevance feedback. Boolean search engines usually only return the exact same item regardless of order, although the term boolean search engine may refer only to the use of boolean style syntax (use of operators AND, OR, NOT, and XOR) in a probabilistic context.
To provide a set of matching items that are sorted by several criteria quickly, search engines will usually collect metadata about the group of items being considered before through a process called indexing. An index usually requires a smaller amount of computer storage, which is why some search engines only store indexed information and not the full content of each item, and instead provide a method of navigating to items on search engine results pages. Alternatively, search engines can keep a copy of each item in the cache so that users can view the state of the item at that time indexed or for archival purposes or to make the process repeat work more efficiently and quickly.
Other types of search engines do not store indexes. Crawlers, or search engine spider types (aka real-time search engines) can collect and rate items on search queries, dynamically consider additional items based on the contents of the original item (known as seed, or seed URL in the case of Internet crawlers). Meta search engines do not store indexes or cache and instead only reuse the index or the results of one or more other search engines to provide a collection of the collected end results.
Maps Search engine (computing)
Search engine type
- By source
- Desktop search
- Combined search
- Human search engine
- Metasearch engine
- Multisearch
- Search collector
- Web search engine
- With content type
- Full text search
- Image search
- Video search engine
- With interface
- Additional searches
- Instant answer
- Semantic search
- Selection based search
- By topic
- The bibliographic database
- Company search
- Intake of medical literature
- Vertical search
See also
References
Source of the article : Wikipedia
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