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<title>Search engine (computing)</title>

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<span id="openzim-page-title" class="mw-page-title-main"><span class="mw-page-title-main">Search engine (computing)</span></span>

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<p>In <a href="Computing" title="Computing">computing</a>, a <b>search engine</b> is an information retrieval software system designed to help find information stored on one or more <a href="Computer_system" class="mw-redirect" title="Computer system">computer systems</a>. Search engines discover, crawl, transform, and store information for retrieval and presentation in response to user queries. The search results are usually presented in a list and are commonly called <i>hits</i>. The most widely used type of search engine is a <a href="Web_search_engine" class="mw-redirect" title="Web search engine">web search engine</a>, which searches for information on the <a href="World_Wide_Web" title="World Wide Web">World Wide Web</a>.

</p><p>A search engine normally consists of four components, as follows: a search interface, a crawler (also known as a spider or bot), an indexer, and a database. The crawler traverses a document collection, deconstructs document text, and assigns surrogates for storage in the search engine index. Online search engines store images, link data and metadata for the document.

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<div class="mw-heading mw-heading2"><h2 id="How_search_engines_work">How search engines work</h2></div>

<p>Search engines provide an <a href="Interface_(computer_science)" class="mw-redirect" title="Interface (computer science)">interface</a> to a group of items that enables users to specify criteria about an item of interest and have the engine find the matching items. The criteria are referred to as a <a href="Web_search_query" class="mw-redirect" title="Web search query">search query</a>. In the case of text search engines, the search query is typically expressed as a set of words that identify the desired <a href="Concept" title="Concept">concept</a> that one or more <a href="Document" title="Document">documents</a> may contain.<sup id="cite_ref-1" class="reference"><a href="#cite_note-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup> There are several styles of search query <a href="Syntax" title="Syntax">syntax</a> that vary in strictness. It can also switch names within the search engines from previous sites. Whereas some text search engines require users to enter two or three words separated by <a href="Whitespace_(computer_science)" class="mw-redirect" title="Whitespace (computer science)">white space</a>, other search engines may enable users to specify entire documents, pictures, sounds, and various forms of <a href="Natural_language" title="Natural language">natural language</a>. Some search engines apply improvements to search queries to increase the likelihood of providing a quality set of items through a process known as <a href="Query_expansion" title="Query expansion">query expansion</a>. <a href="Query_understanding" title="Query understanding">Query understanding</a> methods can be used as standardized query language.

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<p>The list of items that meet the criteria specified by the query is typically sorted, or ranked. Ranking items by relevance (from highest to lowest) reduces the time required to find the desired information. <a href="Probability" title="Probability">Probabilistic</a> search engines rank items based on measures of <a href="String_metric" title="String metric">similarity</a> (between each item and the query, typically on a scale of 1 to 0, 1 being most similar) and sometimes <a href="Popularity" title="Popularity">popularity</a> or <a href="Authority" title="Authority">authority</a> (see <a href="Bibliometrics" title="Bibliometrics">Bibliometrics</a>) or use <a href="Relevance_feedback" title="Relevance feedback">relevance feedback</a>. <a href="Boolean_logic" class="mw-redirect" title="Boolean logic">Boolean</a> search engines typically only return items which match exactly without regard to order, although the term <i>Boolean search engine</i> may simply refer to the use of Boolean-style syntax (the use of operators <a href="Logical_conjunction" title="Logical conjunction">AND</a>, <a href="Logical_disjunction" title="Logical disjunction">OR</a>, NOT, and <a href="Exclusive_nor_gate" class="mw-redirect" title="Exclusive nor gate">XOR</a>) in a probabilistic context.

</p><p>To provide a set of matching items that are sorted according to some criteria quickly, a search engine will typically collect <a href="Metadata" title="Metadata">metadata</a> about the group of items under consideration beforehand through a process referred to as <a href="Index_(search_engine)" class="mw-redirect" title="Index (search engine)">indexing</a>. The index typically requires a smaller amount of <a href="Computer_storage" class="mw-redirect" title="Computer storage">computer storage</a>, which is why some search engines only store the indexed information and not the full content of each item, and instead provide a method of navigating to the items in the <a href="Serpent_(album)" class="mw-redirect" title="Serpent (album)">search engine result page</a>. Alternatively, the search engine may store a copy of each item in a <a href="Cache_(computing)" title="Cache (computing)">cache</a> so that users can see the state of the item at the time it was indexed or for archive purposes or to make repetitive processes work more efficiently and quickly.<sup id="cite_ref-2" class="reference"><a href="#cite_note-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup>

</p><p>Other types of search engines do not store an index. <a href="Web_crawler" title="Web crawler">Crawler</a>, or spider type search engines (a.k.a. real-time search engines) may collect and assess items at the time of the search query, dynamically considering additional items based on the contents of a starting item (known as a seed, or seed URL in the case of an Internet crawler). <a href="Meta_search_engine" class="mw-redirect" title="Meta search engine">Meta search engines</a> store neither an index nor a cache and instead simply reuse the index or results of one or more other search engine to provide an aggregated, final set of results.

</p><p>Database size, which had been a significant marketing feature through the early 2000s, was similarly displaced by emphasis on relevancy ranking, the methods by which search engines attempt to sort the best results first. Relevancy ranking first became a major issue <abbr title="circa">c.</abbr><span style="white-space:nowrap;"> 1996</span>, when it became apparent that it was impractical to review full lists of results. Consequently, <a href="Algorithm" title="Algorithm">algorithms</a> for relevancy ranking have continuously improved. Google's <a href="PageRank" title="PageRank">PageRank</a> method for ordering the results has received the most press, but all major search engines continually refine their ranking methodologies with a view toward improving the ordering of results. As of 2006, search engine rankings are more important than ever, so much so that an industry has developed ("<a href="Search_engine_optimization" title="Search engine optimization">search engine optimizers</a>", or "SEO") to help web-developers improve their search ranking, and an entire body of <a href="Case_law" title="Case law">case law</a> has developed around matters that affect search engine rankings, such as use of <a href="Trademarks" class="mw-redirect" title="Trademarks">trademarks</a> in <a href="Metatags" class="mw-redirect" title="Metatags">metatags</a>. The sale of search rankings by some search engines has also created controversy among librarians and consumer advocates.<sup id="cite_ref-3" class="reference"><a href="#cite_note-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup>

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<p>Search engine experience for users continues to be enhanced. Google's addition of the <a href="Knowledge_Graph_(Google)" title="Knowledge Graph (Google)">Google Knowledge Graph</a> has had wider ramifications for the Internet, possibly even limiting certain websites traffic, for example Wikipedia. By pulling information and presenting it on Google's page, some argue that it can negatively affect other sites. However, there have been no major concerns.<sup id="cite_ref-4" class="reference"><a href="#cite_note-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup>

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<div class="mw-heading mw-heading2"><h2 id="Search_engine_categories">Search engine categories</h2></div>

<div class="mw-heading mw-heading3"><h3 id="Web_search_engines">Web search engines</h3></div>

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</style><div role="note" class="hatnote navigation-not-searchable">Main article: <a href="Search_engine" title="Search engine">Search engine</a></div>

<p>Search engines that are expressly designed for searching web pages, documents, and images were developed to facilitate searching through a large, nebulous blob of unstructured resources. They are engineered to follow a multi-stage process: crawling the infinite stockpile of pages and documents to skim the figurative foam from their contents, indexing the foam/buzzwords in a sort of semi-structured form (database or something), and at last, resolving user entries/queries to return mostly relevant results and links to those skimmed documents or pages from the inventory.

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<div class="mw-heading mw-heading4"><h4 id="Crawl">Crawl</h4></div>

<p>In the case of a wholly textual search, the first step in classifying web pages is to find an ‘index item’ that might relate expressly to the ‘search term.’ In the past, search engines began with a small list of URLs as a so-called seed list, fetched the content, and parsed the links on those pages for relevant information, which subsequently provided new links. The process was highly cyclical and continued until enough pages were found for the searcher's use.

These days, a continuous crawl method is employed as opposed to an incidental discovery based on a seed list. The crawl method is an extension of aforementioned discovery method.

</p><p>Most search engines use sophisticated scheduling algorithms to “decide” when to revisit a particular page, to appeal to its relevance. These algorithms range from constant visit-interval with higher priority for more frequently changing pages to adaptive visit-interval based on several criteria such as frequency of change, popularity, and overall quality of site. The speed of the web server running the page as well as resource constraints like amount of hardware or bandwidth also figure in.

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<p>Pages that are discovered by web crawls are often distributed and fed into another computer that creates a map of resources uncovered. The bunchy clustermass looks a little like a graph, on which the different pages are represented as small nodes that are connected by links between the pages.

The excess of data is stored in multiple data structures that permit quick access to said data by certain algorithms that compute the popularity score of pages on the web based on how many links point to a certain web page, which is how people can access any number of resources concerned with diagnosing psychosis. Another example would be the accessibility/rank of web pages containing information on Mohamed Morsi versus the very best attractions to visit in Cairo after simply entering ‘Egypt’ as a search term. One such algorithm, <a href="PageRank" title="PageRank">PageRank</a>, proposed by Google founders Larry Page and Sergey Brin, is well known and has attracted a lot of attention because it highlights repeat mundanity of web searches courtesy of students that don't know how to properly research subjects on Google.

</p><p>The idea of doing link analysis to compute a popularity rank is older than PageRank. However, In October 2014, Google’s John Mueller confirmed that Google is not going to be updating it (Page Rank) going forward. Other variants of the same idea are currently in use – grade schoolers do the same sort of computations in picking kickball teams. These ideas can be categorized into three main categories: rank of individual pages and nature of web site content. Search engines often differentiate between internal links and external links, because web content creators are not strangers to shameless self-promotion. Link map data structures typically store the anchor text embedded in the links as well, because anchor text can often provide a “very good quality” summary of a web page's content.

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<div class="mw-heading mw-heading3"><h3 id="Database_Search_Engines">Database Search Engines</h3></div>

<p>Searching for text-based content in databases presents a few special challenges from which a number of specialized search engines flourish. Databases can be slow when solving complex queries (with multiple logical or string matching arguments). Databases allow pseudo-logical queries which full-text searches do not use. There is no crawling necessary for a database since the data is already structured. However, it is often necessary to index the data in a more economized form to allow a more expeditious search.

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<div class="mw-heading mw-heading3"><h3 id="Mixed_Search_Engines">Mixed Search Engines</h3></div>

<p>Sometimes, data searched contains both database content and web pages or documents. Search engine technology has developed to respond to both sets of requirements. Most mixed search engines are large Web search engines, like Google. They search both through structured and <a href="Unstructured_data" title="Unstructured data">unstructured data</a> sources. Take for example, the word ‘ball.’ In its simplest terms, it returns more than 40 variations on Wikipedia alone. Did you mean a ball, as in the social gathering/dance? A soccer ball? The ball of the foot? Pages and documents are crawled and indexed in a separate index. Databases are indexed also from various sources. Search results are then generated for users by querying these multiple indices in parallel and compounding the results according to “rules.”

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<div class="mw-heading mw-heading2"><h2 id="History_of_search_technology">History of search technology</h2></div>

<div role="note" class="hatnote navigation-not-searchable">Further information: <a href="History_of_web_search_engines" class="mw-redirect" title="History of web search engines">History of web search engines</a> and <a href="Timeline_of_web_search_engines" title="Timeline of web search engines">Timeline of web search engines</a></div>

<div class="mw-heading mw-heading3"><h3 id="The_Memex">The Memex</h3></div>

<p>The concept of hypertext and a memory extension originates from an article that was published in <i><a href="The_Atlantic_Monthly" class="mw-redirect" title="The Atlantic Monthly">The Atlantic Monthly</a></i> in July 1945 written by <a href="Vannevar_Bush" title="Vannevar Bush">Vannevar Bush</a>, titled "<a href="As_We_May_Think" title="As We May Think">As We May Think</a>". Within this article Vannevar urged scientists to work together to help build a body of knowledge for all mankind. He then proposed the idea of a virtually limitless, fast, reliable, extensible, associative memory storage and retrieval system. He named this device a <a href="Memex" title="Memex">memex</a>.<sup id="cite_ref-5" class="reference"><a href="#cite_note-5"><span class="cite-bracket">[</span>5<span class="cite-bracket">]</span></a></sup>

</p><p>Bush regarded the notion of “associative indexing” as his key conceptual contribution. As he explained, this was “a provision whereby any item may be caused at will to select immediately and automatically another. This is the essential feature of the memex. The process of tying two items together is the important thing.<sup id="cite_ref-6" class="reference"><a href="#cite_note-6"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup>

</p><p>All of the documents used in the memex would be in the form of microfilm copy acquired as such or, in the case of personal records, transformed to microfilm by the machine itself. Memex would also employ new retrieval techniques based on a new kind of associative indexing the basic idea of which is a provision whereby any item may be caused at will to select immediately and automatically another to create personal "trails" through linked documents. The new procedures, that Bush anticipated facilitating information storage and retrieval would lead to the development of wholly new forms of the encyclopedia.

</p><p>The most important mechanism, conceived by Bush, is the associative trail. It would be a way to create a new linear sequence of microfilm frames across any arbitrary sequence of microfilm frames by creating a chained sequence of links in the way just described, along with personal comments and side trails.

</p><p>In 1965, Bush took part in the project INTREX of MIT, for developing technology for mechanization the processing of information for library use. In his 1967 essay titled "Memex Revisited", he pointed out that the development of the digital computer, the transistor, the video, and other similar devices had heightened the feasibility of such mechanization, but costs would delay its achievements.<sup id="cite_ref-7" class="reference"><a href="#cite_note-7"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup>

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<div class="mw-heading mw-heading3"><h3 id="SMART">SMART</h3></div>

<p>Gerard Salton, who died on August 28 of 1995, was the father of modern search technology. His teams at Harvard and Cornell developed the SMART informational retrieval system. Salton's Magic Automatic Retriever of Text included important concepts like the <a href="Vector_space_model" title="Vector space model">vector space model</a>, <a href="Inverse_document_frequency" class="mw-redirect" title="Inverse document frequency">Inverse Document Frequency</a> (IDF), Term Frequency (TF), term discrimination values, and relevancy feedback mechanisms.

</p><p>He authored a 56-page book called <i>A Theory of Indexing</i> which explained many of his tests, upon which search is still largely based.

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<div class="mw-heading mw-heading3"><h3 id="String_Search_Engines">String Search Engines</h3></div>

<p>In 1987, an article was published detailing the development of a character string search engine (SSE) for rapid text retrieval on a double-metal 1.6-μm n-well CMOS solid-state circuit with 217,600 transistors lain out on a 8.62x12.76-mm die area. The SSE accommodated a novel string-search architecture which combines a 512-stage finite-state automaton (FSA) logic with a content addressable memory (CAM) to achieve an approximate string comparison of 80 million strings per second. The CAM cell consisted of four conventional static RAM (SRAM) cells and a read/write circuit. Concurrent comparison of 64 stored strings with variable length was achieved in 50 ns for an input text stream of 10 million characters/s, permitting performance despite the presence of single character errors in the form of character codes. Furthermore, the chip allowed nonanchor string search and variable-length `don't care' (VLDC) string search.<sup id="cite_ref-8" class="reference"><a href="#cite_note-8"><span class="cite-bracket">[</span>8<span class="cite-bracket">]</span></a></sup>

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<div class="mw-heading mw-heading3"><h3 id="By_source">By source</h3></div>

<ul><li><a href="Database_search_engine" title="Database search engine">Database search engine</a></li>

<li><a href="Desktop_search" title="Desktop search">Desktop search</a></li>

<li><a href="Enterprise_search" title="Enterprise search">Enterprise search</a></li>

<li><a href="Federated_search" title="Federated search">Federated search</a></li>

<li><a href="Human_search_engine" title="Human search engine">Human search engine</a></li>

<li><a href="Metasearch_engine" title="Metasearch engine">Metasearch engine</a></li>

<li><a href="Multisearch" title="Multisearch">Multisearch</a></li>

<li><a href="Search_aggregator" title="Search aggregator">Search aggregator</a></li>

<li><a href="Web_search_engine" class="mw-redirect" title="Web search engine">Web search engine</a></li></ul>

<div class="mw-heading mw-heading3"><h3 id="By_content_type">By content type</h3></div>

<ul><li><a href="Audio_search" class="mw-redirect" title="Audio search">Audio search engine</a></li>

<li><a href="Full_text_search" class="mw-redirect" title="Full text search">Full text search</a></li>

<li><a href="Image_search" class="mw-redirect" title="Image search">Image search</a></li>

<li><a href="Video_search_engine" title="Video search engine">Video search engine</a></li></ul>

<div class="mw-heading mw-heading3"><h3 id="By_interface">By interface</h3></div>

<ul><li><a href="Incremental_search" title="Incremental search">Incremental search</a></li>

<li>Instant answer</li>

<li><a href="Semantic_search" title="Semantic search">Semantic search</a></li>

<li><a href="Selection-based_search" title="Selection-based search">Selection-based search</a></li>

<li><a href="Voice_Search" class="mw-redirect" title="Voice Search">Voice Search</a></li></ul>

<div class="mw-heading mw-heading3"><h3 id="By_topic">By topic</h3></div>

<ul><li><a href="Bibliographic_database" title="Bibliographic database">Bibliographic database</a></li>

<li><a href="Enterprise_search" title="Enterprise search">Enterprise search</a></li>

<li><a href="Medical_literature_retrieval" title="Medical literature retrieval">Medical literature retrieval</a></li>

<li><a href="Vertical_search" title="Vertical search">Vertical search</a></li></ul>

<div class="mw-heading mw-heading3"><h3 id="Others">Others</h3></div>

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<ul><li><a href="Automatic_summarization" title="Automatic summarization">Automatic summarization</a></li>

<li><a href="Emanuel_Goldberg" title="Emanuel Goldberg">Emanuel Goldberg</a> (inventor of early search engine)</li>

<li><a href="Index_(search_engine)" class="mw-redirect" title="Index (search engine)">Index (search engine)</a></li>

<li><a href="Inverted_index" title="Inverted index">Inverted index</a></li>

<li><a href="List_of_search_engines" title="List of search engines">List of search engines</a></li>

<li><a href="Search_as_a_service" title="Search as a service">Search as a service</a></li>

<li><a href="Search_engine_indexing" title="Search engine indexing">Search engine indexing</a></li>

<li><a href="Search_engine_optimization" title="Search engine optimization">Search engine optimization</a></li>

<li><a href="Search_suggest_drop-down_list" title="Search suggest drop-down list">Search suggest drop-down list</a></li>

<li><a href="Solver_(computer_science)" class="mw-redirect" title="Solver (computer science)">Solver (computer science)</a></li>

<li><a href="Spamdexing" title="Spamdexing">Spamdexing</a></li>

<li><a href="Text_mining" title="Text mining">Text mining</a></li>

<li><a href="Web_crawler" title="Web crawler">Web crawler</a></li>

<li><a href="Word-sense_disambiguation" title="Word-sense disambiguation">Word-sense disambiguation</a> (dealing with <a href="Ambiguity" title="Ambiguity">Ambiguity</a>)</li></ul>

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<div class="mw-heading mw-heading2"><h2 id="References">References</h2></div>

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</style><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://paulandre.com/understanding-search-queries/">"Understanding Search Queries: How Search Engines Match Your Words to Relevant Documents"</a>. <i>paulandre.com</i>.</cite></span>

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<li id="cite_note-2"><span class="mw-cite-backlink"><b><a href="#cite_ref-2">^</a></b></span> <span class="reference-text"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://edu.gcfglobal.org/en/internetbasics/using-search-engines/1/">"Internet Basics: Using Search Engines"</a>. <i>GCFGlobal.org</i><span class="reference-accessdate">. Retrieved <span class="nowrap">2022-07-11</span></span>.</cite></span>

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<li id="cite_note-3"><span class="mw-cite-backlink"><b><a href="#cite_ref-3">^</a></b></span> <span class="reference-text"><cite id="CITEREFStross2009" class="citation book cs1">Stross, Randall (22 September 2009). <a rel="nofollow" class="external text" href="https://books.google.com/books?id=xOk3EIUW9VgC"><i>Planet Google: One Company's Audacious Plan to Organize Everything We Know</i></a>. Simon and Schuster. <a href="ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <bdi>978-1-4165-4696-2</bdi><span class="reference-accessdate">. Retrieved <span class="nowrap">9 December</span> 2012</span>.</cite></span>

</li>

<li id="cite_note-4"><span class="mw-cite-backlink"><b><a href="#cite_ref-4">^</a></b></span> <span class="reference-text"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://www.dailydot.com/unclick/wikipedia-falling-traffic-meaning/">"What do we make of Wikipedia's falling traffic?"</a>. <i>The Daily Dot</i>. 2014-01-08<span class="reference-accessdate">. Retrieved <span class="nowrap">2020-11-01</span></span>.</cite></span>

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<li id="cite_note-5"><span class="mw-cite-backlink"><b><a href="#cite_ref-5">^</a></b></span> <span class="reference-text"><cite id="CITEREFYeo2007" class="citation journal cs1">Yeo, Richard (30 January 2007). "Before Memex: Robert Hooke, John Locke, and Vannevar Bush on External Memory". <i>Science in Context</i>. <b>20</b> (1): 21. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1017%2FS0269889706001128">10.1017/S0269889706001128</a>. <a href="Hdl_(identifier)" class="mw-redirect" title="Hdl (identifier)">hdl</a>:<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://hdl.handle.net/10072%2F15207">10072/15207</a></span>. <a href="S2CID_(identifier)" class="mw-redirect" title="S2CID (identifier)">S2CID</a> <a rel="nofollow" class="external text" href="https://api.semanticscholar.org/CorpusID:2378301">2378301</a>.</cite></span>

</li>

<li id="cite_note-6"><span class="mw-cite-backlink"><b><a href="#cite_ref-6">^</a></b></span> <span class="reference-text"><cite id="CITEREFYeo2007" class="citation journal cs1">Yeo, Richard (30 January 2007). "Before Memex: Robert Hooke, John Locke, and Vannevar Bush on External Memory". <i>Science in Context</i>. <b>20</b> (1): <span class="nowrap">21–</span>47. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1017%2FS0269889706001128">10.1017/S0269889706001128</a>. <a href="Hdl_(identifier)" class="mw-redirect" title="Hdl (identifier)">hdl</a>:<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://hdl.handle.net/10072%2F15207">10072/15207</a></span>. <a href="S2CID_(identifier)" class="mw-redirect" title="S2CID (identifier)">S2CID</a> <a rel="nofollow" class="external text" href="https://api.semanticscholar.org/CorpusID:2378301">2378301</a>The example Bush gives is a quest to find information on the relative merits of the Turkish short bow and the English long bow in the crusades</cite><span class="cs1-maint citation-comment"><code class="cs1-code">{{cite journal}}</code>: CS1 maint: postscript (link)</span></span>

</li>

<li id="cite_note-7"><span class="mw-cite-backlink"><b><a href="#cite_ref-7">^</a></b></span> <span class="reference-text"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://web.archive.org/web/20210107233415/https://history-computer.com/Internet/Dreamers/Bush.html">"The MEMEX of Vannevar Bush"</a>. 4 January 2021. Archived from <a rel="nofollow" class="external text" href="http://history-computer.com/Internet/Dreamers/Bush.html">the original</a> on 7 January 2021<span class="reference-accessdate">. Retrieved <span class="nowrap">12 August</span> 2023</span>.</cite></span>

</li>

<li id="cite_note-8"><span class="mw-cite-backlink"><b><a href="#cite_ref-8">^</a></b></span> <span class="reference-text"><cite id="CITEREFYamadaHirata,_M.Nagai,_H.Takahashi,_K.1987" class="citation journal cs1">Yamada, H.; Hirata, M.; Nagai, H.; Takahashi, K. (Oct 1987). "A high-speed string-search engine". <i>IEEE Journal of Solid-State Circuits</i>. <b>22</b> (5). IEEE: <span class="nowrap">829–</span>834. <a href="Bibcode_(identifier)" class="mw-redirect" title="Bibcode (identifier)">Bibcode</a>:<a rel="nofollow" class="external text" href="https://ui.adsabs.harvard.edu/abs/1987IJSSC..22..829Y">1987IJSSC..22..829Y</a>. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1109%2FJSSC.1987.1052819">10.1109/JSSC.1987.1052819</a>.</cite></span>

</li>

</ol></div></div>

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</style></div><div role="navigation" class="navbox" aria-labelledby="Internet_search65" style="padding:3px"><table class="nowraplinks mw-collapsible autocollapse navbox-inner" style="border-spacing:0;background:transparent;color:inherit"><tbody><tr><th scope="col" class="navbox-title" colspan="2"><style data-mw-deduplicate="TemplateStyles:r1239400231">

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</style><div id="Internet_search65" style="font-size:114%;margin:0 4em"><a href="Internet_search" class="mw-redirect" title="Internet search">Internet search</a></div></th></tr><tr><th scope="row" class="navbox-group" style="width:1%">Types</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Web_search_engine" class="mw-redirect" title="Web search engine">Web search engine</a> (<a href="List_of_search_engines" title="List of search engines">List</a>)</li>

<li><a href="Metasearch_engine" title="Metasearch engine">Metasearch engine</a></li>

<li><a href="Multimedia_search" title="Multimedia search">Multimedia search</a></li>

<li><a href="Collaborative_search_engine" title="Collaborative search engine">Collaborative search engine</a></li>

<li><a href="Cross-language_search" class="mw-redirect" title="Cross-language search">Cross-language search</a></li>

<li><a href="Local_search_(Internet)" title="Local search (Internet)">Local search</a></li>

<li><a href="Vertical_search" title="Vertical search">Vertical search</a></li>

<li><a href="Social_search" title="Social search">Social search</a></li>

<li><a href="Image_retrieval" title="Image retrieval">Image search</a></li>

<li><a href="Audio_search_engine" title="Audio search engine">Audio search</a></li>

<li><a href="Video_search_engine" title="Video search engine">Video search engine</a></li>

<li><a href="Enterprise_search" title="Enterprise search">Enterprise search</a></li>

<li><a href="Semantic_search" title="Semantic search">Semantic search</a></li>

<li><a href="Natural_language_search_engine" class="mw-redirect" title="Natural language search engine">Natural language search engine</a></li>

<li><a href="Voice_search" title="Voice search">Voice search</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Tools</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Cross-language_information_retrieval" title="Cross-language information retrieval">Cross-language information retrieval</a></li>

<li><a href="Search_by_sound" title="Search by sound">Search by sound</a></li>

<li><a href="Search_engine_marketing" title="Search engine marketing">Search engine marketing</a></li>

<li><a href="Search_engine_optimization" title="Search engine optimization">Search engine optimization</a></li>

<li><a href="Evaluation_measures_(information_retrieval)" title="Evaluation measures (information retrieval)">Evaluation measures</a></li>

<li>Search oriented architecture</li>

<li><a href="Selection-based_search" title="Selection-based search">Selection-based search</a></li>

<li><a href="Document_retrieval" title="Document retrieval">Document retrieval</a></li>

<li><a href="Text_mining" title="Text mining">Text mining</a></li>

<li><a href="Web_crawler" title="Web crawler">Web crawler</a></li>

<li><a href="Multisearch" title="Multisearch">Multisearch</a></li>

<li><a href="Federated_search" title="Federated search">Federated search</a></li>

<li><a href="Search_aggregator" title="Search aggregator">Search aggregator</a></li>

<li><a href="Index_(search_engine)" class="mw-redirect" title="Index (search engine)">Index</a>/<a href="Web_indexing" title="Web indexing">Web indexing</a></li>

<li><a href="Focused_crawler" title="Focused crawler">Focused crawler</a></li>

<li><a href="Spider_trap" title="Spider trap">Spider trap</a></li>

<li><a href="Robots_exclusion_standard" class="mw-redirect" title="Robots exclusion standard">Robots exclusion standard</a></li>

<li><a href="Distributed_web_crawling" title="Distributed web crawling">Distributed web crawling</a></li>

<li><a href="Web_archiving" title="Web archiving">Web archiving</a></li>

<li><a href="Website_mirroring_software" class="mw-redirect" title="Website mirroring software">Website mirroring software</a></li>

<li><a href="Web_query" title="Web query">Web query</a></li>

<li><a href="Web_query_classification" title="Web query classification">Web query classification</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Protocols<br>and standards</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">

<li><a href="Search/Retrieve_Web_Service" title="Search/Retrieve Web Service">Search/Retrieve Web Service</a></li>

<li><a href="Search/Retrieve_via_URL" title="Search/Retrieve via URL">Search/Retrieve via URL</a></li>

<li><a href="OpenSearch_(specification)" title="OpenSearch (specification)">OpenSearch</a></li>

<li><a href="Representational_State_Transfer" class="mw-redirect" title="Representational State Transfer">Representational State Transfer</a></li>

<li><a href="Wide_area_information_server" title="Wide area information server">Wide area information server</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">See also</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul>

<li><a href="Desktop_search" title="Desktop search">Desktop search</a></li>

<li><a href="Online_search" title="Online search">Online search</a></li></ul>

</div></td></tr></tbody></table></div>

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</style></div><div role="navigation" class="navbox authority-control" aria-labelledby="Authority_control_databases_frameless&#124;text-top&#124;10px&#124;alt=Edit_this_at_Wikidata&#124;link=https&#58;//www.wikidata.org/wiki/Q19541#identifiers&#124;class=noprint&#124;Edit_this_at_Wikidata1523" style="padding:3px"><table class="nowraplinks hlist mw-collapsible autocollapse navbox-inner" style="border-spacing:0;background:transparent;color:inherit"><tbody><tr><th scope="col" class="navbox-title" colspan="2"><div id="Authority_control_databases_frameless&#124;text-top&#124;10px&#124;alt=Edit_this_at_Wikidata&#124;link=https&#58;//www.wikidata.org/wiki/Q19541#identifiers&#124;class=noprint&#124;Edit_this_at_Wikidata1523" style="font-size:114%;margin:0 4em">Authority control databases </div></th></tr><tr><th scope="row" class="navbox-group" style="width:1%">International</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"><ul><li><span class="uid"><a rel="nofollow" class="external text" href="https://id.worldcat.org/fast/1110372">FAST</a></span></li></ul></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">National</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"><ul><li><span class="uid"><a rel="nofollow" class="external text" href="https://d-nb.info/gnd/4423007-2">Germany</a></span></li><li><span class="uid"><span class="rt-commentedText tooltip tooltip-dotted" title="Search engines"><a rel="nofollow" class="external text" href="https://id.loc.gov/authorities/sh00001050">United States</a></span></span></li><li><span class="uid"><span class="rt-commentedText tooltip tooltip-dotted" title="Moteurs de recherche"><a rel="nofollow" class="external text" href="https://catalogue.bnf.fr/ark:/12148/cb13558463d">France</a></span></span></li><li><span class="uid"><span class="rt-commentedText tooltip tooltip-dotted" title="Moteurs de recherche"><a rel="nofollow" class="external text" href="https://data.bnf.fr/ark:/12148/cb13558463d">BnF data</a></span></span></li><li><span class="uid"><a rel="nofollow" class="external text" href="https://id.ndl.go.jp/auth/ndlna/00964483">Japan</a></span></li><li><span class="uid"><a rel="nofollow" class="external text" href="https://www.nli.org.il/en/authorities/987007291618305171">Israel</a></span></li></ul></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Other</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"><ul><li><span class="uid"><a rel="nofollow" class="external text" href="https://lux.collections.yale.edu/view/concept/ab437a05-aef4-4a8e-9621-ef51d9b79234">Yale LUX</a></span></li></ul></div></td></tr></tbody></table></div></div><div><div class="zim-footer">

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