What is a search engine?

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A Web search engine is a search engine designed to search for information on the World Wide Web. Information may consist of web pages, images and other types of files. Some search engines also mine data available in newsbooks, databases, or open directories. Unlike Web directories, which are maintained by human editors, search engines operate algorithmically or are a mixture of algorithmic and human input.

* 1 History
* 2 How Web search engines work
* 3 See also
* 4 References
o 4.1 Notes
o 4.2 Bibliography
o 4.3 External links

Note: "Launch" refers only to web
availability of original crawl-based
web search engine results. For full-list: List of search engines
Year Engine Event
1993 Aliweb Launch
1994 WebCrawler Launch
Infoseek Launch
Lycos Launch
1995 AltaVista Launch (part of DEC)
Magellan Launch (The McKinley Group)
Excite Launch
SAPO Launch
1996 Dogpile Launch
Inktomi Founded
HotBot Founded
Ask Jeeves Founded
1997 Northern Light Launch
Yandex Launch
1998 Google Launch
1999 AlltheWeb Launch
Naver Launch
Teoma Founded
Vivisimo Founded
2000 Baidu Founded
2003 Info.com Launch
2004 Yahoo! Search Final launch
A9.com Launch
2005 MSN Search Final launch
Ask.com Launch
GoodSearch Launch
2006 wikiseek Founded
Quaero Founded
Ask.com Launch
Live Search Launch
ChaCha Beta Launch
Guruji.com Beta Launch
2007 wikiseek Launched
Wikia Search Launched
2008 Cuil Launched

Before there were search engines there was a complete list of all webservers. The list was edited by Tim Berners-Lee and hosted on the CERN webserver. One historical snapshot from 1992 remains[1]. As more and more webservers went online the central list could not keep up. On the NCSA Site new servers were announced under the title "What's New!", but no complete listing existed any more[2].

The very first tool used for searching on the (pre-web) Internet was Archie.[3] The name stands for "archive" without the "v". It was created in 1990 by Alan Emtage, a student at McGill University in Montreal. The program downloaded the directory listings of all the files located on public anonymous FTP (File Transfer Protocol) sites, creating a searchable database of file names; however, Archie did not index the contents of these sites.

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 (Very Easy Rodent-Oriented Net-wide Index to Computerized Archives) provided a keyword search of most Gopher menu titles in the entire Gopher listings. Jughead (Jonzy's Universal Gopher Hierarchy Excavation And Display) was a tool for obtaining menu information from specific Gopher servers. While the name of the search engine "Archie" was not a reference to the Archie comic book series, "Veronica" and "Jughead" are characters in the series, thus referencing their predecessor.

The first Web search engine was Wandex, a now-defunct index collected by the World Wide Web Wanderer, a web crawler developed by Matthew Gray at MIT in 1993. Another very early search engine, Aliweb, also appeared in 1993. JumpStation (released in early 1994) used a crawler to find web pages for searching, but search was limited to the title of web pages only. One of the first "full text" crawler-based search engines was WebCrawler, which came out in 1994. Unlike its predecessors, it let users search for any word in any webpage, which became the standard for all major search engines since. It was also the first one to be 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 full-text copies of web pages. Information seekers could also browse the directory instead of doing a keyword-based search.

In 1996, Netscape was looking to give a single search engine an exclusive deal to be their featured search engine. There was so much interest that instead a deal was struck with Netscape by 5 of the major search engines, where for $5Million per year each search engine would be in a rotation on the Netscape search engine page. These five engines were: Yahoo!, Magellan, Lycos, Infoseek and Excite.

Search engines were also known as some of the brightest stars in the Internet investing frenzy that occurred in the late 1990s.[4] Several companies entered the market spectacularly, receiving record gains during their initial public offerings. Some have taken down their public search engine, and are marketing enterprise-only editions, such as Northern Light. Many search engine companies were caught up in the dot-com bubble, a speculation-driven market boom that peaked in 1999 and ended in 2001.

Around 2000, the Google search engine rose to prominence.[citation needed] The company achieved better results for many searches with an innovation called PageRank. This iterative algorithm ranks web pages based on the number and PageRank of other web sites and pages that link there, on the premise that good or desirable pages are linked to more than others. Google also maintained a minimalist interface to its search engine. In contrast, many of its competitors embedded a search engine in a web portal.

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 first launched MSN Search (since re-branded Live Search) in the fall of 1998 using search results from Inktomi. In early 1999 the site began to display listings from Looksmart blended with results from Inktomi except for a short time in 1999 when results from AltaVista were used instead. In 2004, Microsoft began a transition to its own search technology, powered by its own web crawler (called msnbot).

As of late 2007, Google was by far the most popular Web search engine worldwide.[5] [6] A number of country-specific search engine companies have become prominent; for example Baidu is the most popular search engine in the People's Republic of China and guruji.com in India.[7]

How Web search engines work
This section does not cite any references or sources.
Please help improve this section by adding citations to reliable sources. Unverifiable material may be challenged and removed. (November 2007)

A search engine operates, in the following order

1. Web crawling
2. Indexing
3. Searching

Web search engines work by storing information about many web pages, which they retrieve from the WWW itself. These pages are retrieved by a Web crawler (sometimes also known as a spider) — an automated Web browser which follows every link it sees. Exclusions can be made by the use of robots.txt. The contents of each page are then analyzed to determine how it should be indexed (for example, words are extracted from the titles, headings, or special fields called meta tags). Data about web pages are stored in an index database for use in later queries. Some search engines, such as Google, store all or part of the source page (referred to as a cache) as well as information about the web pages, whereas others, such as AltaVista, store every word of every page they find. This cached page always holds the actual search text since it is the one that was actually indexed, so it can be very useful when the content of the current page has been updated and the search terms are no longer in it. This problem might be considered to be a mild form of linkrot, and Google's handling of it increases usability by satisfying user expectations that the search terms will be on the returned webpage. This satisfies the principle of least astonishment since the user normally expects the search terms to be on the returned pages. Increased search relevance makes these cached pages very useful, even beyond the fact that they may contain data that may no longer be available elsewhere.

When a user enters a query into a search engine (typically by using key words), the engine examines its index and provides a listing of best-matching web pages according to its criteria, usually with a short summary containing the document's title and sometimes parts of the text. Most search engines support the use of the boolean operators AND, OR and NOT to further specify the search query. Some search engines provide an advanced feature called proximity search which allows users to define the distance between keywords.

The usefulness of a search engine depends on the relevance of the result set it gives back. While there may be millions of webpages 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.

Most Web search engines are commercial ventures supported by advertising revenue and, as a result, some employ the practice of allowing advertisers to pay money to have their listings ranked higher in search results. Those search engines which do not accept money for their search engine 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.

Revenue in the web search portals industry is projected to grow in 2008 by 13.4 percent, with broadband connections expected to rise by 15.1 percent. Between 2008 and 2012, industry revenue is projected to rise by 56 percent as Internet penetration still has some way to go to reach full saturation in American households. Furthermore, broadband services are projected to account for an ever increasing share of domestic Internet users, rising to 118.7 million by 2012, with an increasing share accounted for by fiber-optic and high speed cable lines.[8]

See also

* Index (search engine)
* List of search engines
* Local search (Internet)
* Metasearch engine
* OpenSearch
* Search engine marketing
* Search engine optimization
* Search oriented architecture
* Semantic Web
* Social search
* Spell checker
* Web indexing
* Web search query
* Website Parse Template



The footnotes below are given in support of the statements above. Because some facts are proprietary secrets held by private companies and therefore not documented in journals, such facts are reasoned from facts that are public.

* GBMW: Reports of 30-day punishment, re: Car maker BMW had its German website bmw.de delisted from Google, such as: Slashdot-BMW (05-Feb-2006).
* INSIZ: Maximum size of webpages indexed by MSN/Google/Yahoo! ("100-kb limit"): Max Page-size (28-Apr-2006).

1. ^ http://www.w3.org/History/19921103-hypertext/hypertext/DataSources/WWW/Servers.html
2. ^ http://home.mcom.com/home/whatsnew/whats_new_0294.html
3. ^ "Internet History - Search Engines" (from Search Engine Watch), Universiteit Leiden, Netherlands, September 2001, web: LeidenU-Archie.
4. ^ Gandal, Neil (2001). "The dynamics of competition in the internet search engine market". International Journal of Industrial Organization 19 (7): 1103–1117. doi:10.1016/S0167-7187(01)00065-0.
5. ^ Nielsen NetRatings: August 2007 Search Share Puts Google On Top, Microsoft Holding Gains, SearchEngineLand, September 21, 2007
6. ^ comScore: August 2007 Google Top Worldwide Search Engine; Baidu Beats Microsoft
7. ^ "MSN Money - BIDU". MSN Money. Retrieved on 2006-05-11.
8. ^ March 2008, The Recession List – Top 10 Industries To Fly And Flop In 2008, IBISWorld


* For a more detailed history of early search engines, see Search Engine Birthdays (from Search Engine Watch), Chris Sherman, September 2003.
* Steve Lawrence; C. Lee Giles (1999). "Accessibility of information on the web". Nature 400: 107. doi:10.1038/21987.
* Levene, Mark (2005). An Introduction to Search Engines and Web Navigation. Pearson.
* Hock, Randolph (2007). The Extreme Searcher's Handbook. ISBN 978-0-910965-76-7
* Javed Mostafa (February 2005). "Seeking Better Web Searches". Scientific American Magazine.
* Ross, Nancy; Wolfram, Dietmar (2000). "End user searching on the Internet: An analysis of term pair topics submitted to the Excite search engine". Journal of the American Society for Information Science 51 (10): 949–958.
* Xie, M.; et al. (1998). "Quality dimensions of Internet search engines". Journal of Information Science 24 (5): 365–372. doi:10.1177/016555159802400509.

External links

* Search Engines at the Open Directory Project
* History of Search Engines
* Research Quality, Publications and Impact in Civil Engineering into the 21st Century. Publish or Perish, Commercial versus Open Access, Internet versus Libraries ? Canadian Journal of Civil Engineering, 34 8: 946-951, 2007.
* Impact of Commercial Search Engines and International Databases on Engineering Teaching and Research, European Journal of Engineering Education, 32 3: 261-269, 2007.

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Categories: Information retrieval | Internet search engines | Internet terminology

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