A WEB SEARCH ENGINE is a software system that is designed to search for information on the World Wide Web. The search results are generally presented in a line of results often referred to as search engine results pages (SERPs). The information may be a mix of web pages , images, and other types of files. Some search engines also mine data available in databases or open directories . Unlike web directories , which are maintained only by human editors, search engines also maintain real-time information by running an algorithm on a web crawler .
* 1 History * 2 How web search engines work
* 3 Market share
* 3.1 East Asia and Russia * 3.2 Europe
* 4 Search engine bias * 5 Customized results and filter bubbles * 6 Christian, Islamic and Jewish search engines * 7 Search engine submission * 8 See also * 9 References * 10 Further reading * 11 External links
Further information: Timeline of web search engines
TIMELINE (FULL LIST )
YEAR ENGINE CURRENT STATUS
1993 W3Catalog Inactive
WWW Worm Inactive
1994 WebCrawler Active, Aggregator
Go.com Inactive, redirects to Disney
1995 AltaVista Inactive, redirected to Yahoo!
Yahoo! Active, Launched as a directory
1996 Dogpile Active, Aggregator
Inktomi Inactive, acquired by Yahoo!
HotBot Active (lycos.com)
Ask Jeeves Active (rebranded ask.com)
1997 Northern Light Inactive
Ixquick Active also as Startpage
MSN Search Active as Bing
empas Inactive (merged with NATE)
1999 AlltheWeb Inactive (URL redirected to Yahoo!)
GenieKnows Active, rebranded Yellowee.com
Teoma Inactive, redirects to Ask.com
2001 Kartoo Inactive
2003 Info.com Active
2005 AOL Search Active
2006 Soso Inactive, redirects to Sogou
2007 wikiseek Inactive
Wikia Search Inactive
2008 Powerset Inactive (redirects to Bing)
Forestle Inactive (redirects to Ecosia)
2009 Bing Active, Launched as rebranded Live Search
Mugurdy Inactive due to a lack of funding
Scout (Goby) Active
Yandex (English) Active
2011 YaCy Active, P2P web search engine
2012 Volunia Inactive
2013 Qwant Active
Coc Coc Active, Vietnamese search engine
Egerin Active, Kurdish / Sorani search engine
2015 Cliqz Active, Browser integrated search engine
Prior to September 1993 the World Wide Web was entirely indexed by hand. There was a list of webservers edited by Tim Berners-Lee and hosted on the CERN webserver. One historical snapshot of the list in 1992 remains, but as more and more web servers went online the central list could no longer keep up. On the NCSA site, new servers were announced under the title "What's New!"
The first tool used for searching content (as opposed to users) on
The rise of Gopher (created in 1991 by Mark McCahill at the University of Minnesota ) led to two new search programs, Veronica and Jughead . Like Archie, they searched the file names and titles stored in Gopher index systems. Veronica (_V_ery _E_asy _R_odent-_O_riented _N_et-wide _I_ndex to _C_omputerized _A_rchives) provided a keyword search of most Gopher menu titles in the entire Gopher listings. Jughead (_J_onzy's _U_niversal _G_opher _H_ierarchy _E_xcavation _A_nd _D_isplay) was a tool for obtaining menu information from specific Gopher servers. While the name of the search engine "Archie Search Engine " was not a reference to the Archie comic book series, "Veronica " and "Jughead " are characters in the series, thus referencing their predecessor.
In the summer of 1993, no search engine existed for the web, though numerous specialized catalogues were maintained by hand. Oscar Nierstrasz at the University of Geneva wrote a series of Perl scripts that periodically mirrored these pages and rewrote them into a standard format. This formed the basis for W3Catalog , the web's first primitive search engine, released on September 2, 1993.
In June 1993, Matthew Gray, then at MIT , produced what was probably the first web robot , the Perl -based World Wide Web Wanderer , and used it to generate an index called 'Wandex'. The purpose of the Wanderer was to measure the size of the World Wide Web, which it did until late 1995. The web's second search engine Aliweb appeared in November 1993. Aliweb did not use a web robot , but instead depended on being notified by website administrators of the existence at each site of an index file in a particular format.
NCSA\'s Mosaic™ - Mosaic (web browser) wasn't the first Web browser. But it was the first to make a major splash. In November 1993, Mosaic v 1.0 broke away from the small pack of existing browsers by including features—like icons, bookmarks, a more attractive interface, and pictures—that made the software easy to use and appealing to "non-geeks."
JumpStation (created in December 1993 by Jonathon Fletcher ) used a web robot to find web pages and to build its index, and used a web form as the interface to its query program. It was thus the first WWW resource-discovery tool to combine the three essential features of a web search engine (crawling, indexing, and searching) as described below. Because of the limited resources available on the platform it ran on, its indexing and hence searching were limited to the titles and headings found in the web pages the crawler encountered.
One of the first "all text" crawler-based search engines was WebCrawler , which came out in 1994. Unlike its predecessors, it allowed users to search for any word in any webpage, which has become the standard for all major search engines since. It was also the first one widely known by the public. Also in 1994, Lycos (which started at Carnegie Mellon University ) was launched and became a major commercial endeavor.
Soon after, many search engines appeared and vied for popularity. These included Magellan , Excite , Infoseek , Inktomi , Northern Light , and AltaVista . Yahoo! was among the most popular ways for people to find web pages of interest, but its search function operated on its web directory , rather than its full-text copies of web pages. Information seekers could also browse the directory instead of doing a keyword-based search.
Search engines were also known as some of the brightest stars in the
By 2000, Yahoo! was providing search services based on Inktomi's search engine. Yahoo! acquired Inktomi in 2002, and Overture (which owned AlltheWeb and AltaVista) in 2003. Yahoo! switched to Google's search engine until 2004, when it launched its own search engine based on the combined technologies of its acquisitions.
Microsoft's rebranded search engine, Bing , was launched on June 1,
2009. On July 29, 2009,
HOW WEB SEARCH ENGINES WORK
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A search engine maintains the following processes in near real time:
Web search engines get their information by web crawling from site to
site. The "spider" checks for the standard filename _robots.txt _,
addressed to it, before sending certain information back to be indexed
depending on many factors, such as the titles, page content,
Cascading Style Sheets (CSS), headings, as evidenced by
Indexing means associating words and other definable tokens found on web pages to their domain names and HTML-based fields. The associations are made in a public database, made available for web search queries. A query from a user can be a single word. The index helps find information relating to the query as quickly as possible.
Some of the techniques for indexing, and caching are trade secrets, whereas web crawling is a straightforward process of visiting all sites on a systematic basis.
Between visits by the _spider_, the cached version of page (some or all the content needed to render it) stored in the search engine working memory is quickly sent to an inquirer. If a visit is overdue, the search engine can just act as a web proxy instead. In this case the page may differ from the search terms indexed. The cached page holds the appearance of the version whose words were indexed, so a cached version of a page can be useful to the web site when the actual page has been lost, but this problem is also considered a mild form of linkrot . High-level architecture of a standard Web crawler
Typically when a user enters a query into a search engine it is a few keywords . The index already has the names of the sites containing the keywords, and these are instantly obtained from the index. The real processing load is in generating the web pages that are the search results list: Every page in the entire list must be weighted according to information in the indexes. Then the top search result item requires the lookup, reconstruction, and markup of the _snippets_ showing the context of the keywords matched. These are only part of the processing each search results web page requires, and further pages (next to the top) require more of this post processing.
Beyond simple keyword lookups, search engines offer their own GUI- or command-driven operators and search parameters to refine the search results. These provide the necessary controls for the user engaged in the feedback loop users create by _filtering_ and _weighting_ while refining the search results, given the initial pages of the first search results. For example, from 2007 the Google.com search engine has allowed one to _filter_ by date by clicking "Show search tools" in the leftmost column of the initial search results page, and then selecting the desired date range. It's also possible to _weight_ by date because each page has a modification time. Most search engines support the use of the boolean operators AND, OR and NOT to help end users refine the search query . Boolean operators are for literal searches that allow the user to refine and extend the terms of the search. The engine looks for the words or phrases exactly as entered. Some search engines provide an advanced feature called proximity search , which allows users to define the distance between keywords. There is also concept-based searching where the research involves using statistical analysis on pages containing the words or phrases you search for. As well, natural language queries allow the user to type a question in the same form one would ask it to a human. A site like this would be ask.com.
The usefulness of a search engine depends on the relevance of the _result set_ it gives back. While there may be millions of web pages that include a particular word or phrase, some pages may be more relevant, popular, or authoritative than others. Most search engines employ methods to rank the results to provide the "best" results first. How a search engine decides which pages are the best matches, and what order the results should be shown in, varies widely from one engine to another. The methods also change over time as Internet usage changes and new techniques evolve. There are two main types of search engine that have evolved: one is a system of predefined and hierarchically ordered keywords that humans have programmed extensively. The other is a system that generates an "inverted index " by analyzing texts it locates. This first form relies much more heavily on the computer itself to do the bulk of the work.
Most Web search engines are commercial ventures supported by advertising revenue and thus some of them allow advertisers to have their listings ranked higher in search results for a fee. Search engines that do not accept money for their search results make money by running search related ads alongside the regular search engine results. The search engines make money every time someone clicks on one of these ads.
The world's most popular search engines (with >1% market share) are:
SEARCH ENGINE MARKET SHARE IN MARCH 2017
Bing 6.92% 6.92
Yahoo! 5.35% 5.35
EAST ASIA AND RUSSIA
Yandex commands a marketshare of 61.9 percent, compared to
Google's 28.3 percent. In China,
SEARCH ENGINE BIAS
Biases can also be a result of social processes, as search engine algorithms are frequently designed to exclude non-normative viewpoints in favor of more "popular" results. Indexing algorithms of major search engines skew towards coverage of U.S.-based sites, rather than websites from non-U.S. countries.
Several scholars have studied the cultural changes triggered by search engines, and the representation of certain controversial topics in their results, such as terrorism in Ireland and conspiracy theories .
CUSTOMIZED RESULTS AND FILTER BUBBLES
CHRISTIAN, ISLAMIC AND JEWISH SEARCH ENGINES
The global growth of the
More than usual _safe search_ filters, these Islamic web portals categorizing websites into being either "halal " or "haram ", based on modern, expert, interpretation of the "Law of Islam" .
While lack of investment and slow pace in technologies in the Muslim
World has hindered progress and thwarted success of an Islamic search
engine, targeting as the main consumers Islamic adherents, projects
Muxlim , a
Other religion-oriented search engines are Jewgle, the Jewish version of Google, and SeekFind.org, which is Christian. SeekFind filters sites that attack or degrade their faith.
SEARCH ENGINE SUBMISSION
Search engine submission is a process in which a webmaster submits a
website directly to a search engine. While search engine submission is
sometimes presented as a way to promote a website, it generally is not
necessary because the major search engines use web crawlers, that will
eventually find most web sites on the
* ^ "RFC 812 - NICNAME/WHOIS". _ietf.org_.
* ^ "World-Wide Web Servers". W3.org. Retrieved 2012-05-14.
* ^ "What\'s New! February 1994". Home.mcom.com. Retrieved
* ^ "
* ^ "Browser Deals Push
* ^ Jansen, B. J. and Rieh, S. (2010) The Seventeen Theoretical
Constructs of Information Searching and Information Retrieval. Journal
of the American Society for Information Sciences and Technology.
* ^ Berkman Center for