Web search engine

Finding information on the World Wide Web had been a difficult and frustrating task, but became much more usable with breakthroughs in search engine technology in the late 1990s.

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.

History

During early development of the web, 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,^[1] but as more and more webservers went online the central list could no longer keep up. On the NCSA site, new servers were announced under the title "What's New!"^[2]

The first tool used for searching on the Internet was Archie.^[3] The name stands for "archive" without the "v". It was created in 1990 by Alan Emtage, Bill Heelan and J. Peter Deutsch, computer science students 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 since the amount of data was so limited it could be readily searched manually.

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.

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.^[4]

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.

JumpStation (created in December 1993^[5] 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.

In 1996, Netscape was looking to give a single search engine an exclusive deal as the featured search engine on Netscape's web browser. There was so much interest that instead Netscape struck deals with five of the major search engines: for $5 million a year, each search engine would be in rotation on the Netscape search engine page. The five engines were Yahoo!, Magellan, Lycos, Infoseek, and Excite.^[6][7]

Google adopted the idea of selling search terms in 1998, from a small search engine company named goto.com. This move had a significant effect on the SE business, which went from struggling to one of the most profitable businesses in the internet.^[8]

Search engines were also known as some of the brightest stars in the Internet investing frenzy that occurred in the late 1990s.^[9] 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, Google's search engine rose to prominence.^[10] The company achieved better results for many searches with an innovation called PageRank, as was explained in the paper Anatomy of a Search Engine written by Sergey Brin and Larry Page, the later founders of Google.^[11] 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. In fact, Google search engine became so popular that spoof engines emerged such as Mystery Seeker.

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 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. For a short time in 1999, MSN Search used results from AltaVista were instead. In 2004, Microsoft began a transition to its own search technology, powered by its own web crawler (called msnbot).

Microsoft's rebranded search engine, Bing, was launched on June 1, 2009. On July 29, 2009, Yahoo! and Microsoft finalized a deal in which Yahoo! Search would be powered by Microsoft Bing technology.

How web search engines work

A search engine operates in the following order:

1. Web crawling
2. Indexing
3. Searching^[12]

Web search engines work by storing information about many web pages, which they retrieve from the HTML markup of the pages. These pages are retrieved by a Web crawler (sometimes also known as a spider) — an automated Web crawler which follows every link on the site. The site owner can exclude specific pages by using robots.txt.

The search engine then analyzes the contents of each page to determine how it should be indexed (for example, words can be extracted from the titles, page content, headings, or special fields called meta tags). Data about web pages are stored in an index database for use in later queries. A query from a user can be a single word. The index helps find information relating to the query as quickly as possible.^[12] 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.^[12] This problem might be considered 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 that the search terms will be on the returned pages. Increased search relevance makes these cached pages very useful as they may contain data that may no longer be available elsewhere.

High-level architecture of a standard Web crawler

When a user enters a query into a search engine (typically by using keywords), 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. The index is built from the information stored with the data and the method by which the information is indexed.^[12] From 2007 the Google.com search engine has allowed one to search by date by clicking "Show search tools" in the leftmost column of the initial search results page, and then selecting the desired date range.^[13] Most search engines support the use of the boolean operators AND, OR and NOT to further specify 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.^[12] 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.^[12] 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.^[14]

Market share

Google is the world's most popular search engine, with a marketshare of 66.44 percent as of December, 2014.^[15] Baidu comes in at second place.^[15]

The world's most popular search engines are:^[16]

East Asia and Russia

East Asian countries and Russia constitute a few places where Google is not the most popular search engine.

Yandex commands a marketshare of 61.9 per cent in Russia, compared to Google's 28.3 percent.^[17] In China, Baidu is the most popular search engine.^[18] South Korea's homegrown search portal, Naver, is used for 70 per cent online searches in the country.^[19] Yahoo! Japan and Yahoo! Taiwan are the most popular avenues for internet search in Japan and Taiwan, respectively.^[20]

Search engine bias

Although search engines are programmed to rank websites based on some combination of their popularity and relevancy, empirical studies indicate various political, economic, and social biases in the information they provide.^[21][22] These biases can be a direct result of economic and commercial processes (e.g., companies that advertise with a search engine can become also more popular in its organic search results), and political processes (e.g., the removal of search results to comply with local laws).^[23] For example, Google will not surface certain Neo-Nazi websites in France and Germany, where Holocaust denial is illegal.

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.^[24] Indexing algorithms of major search engines skew towards coverage of U.S.-based sites, rather than websites from non-U.S. countries.^[22]

Google Bombing is one example of an attempt to manipulate search results for political, social or commercial reasons.

Customized results and filter bubbles

Many search engines such as Google and Bing provide customized results based on the user's activity history. This leads to an effect that has been called a filter bubble. The term describes a phenomenon in which websites use algorithms to selectively guess what information a user would like to see, based on information about the user (such as location, past click behaviour and search history). As a result, websites tend to show only information that agrees with the user's past viewpoint, effectively isolating the user in a bubble that tends to exclude contrary information. Prime examples are Google's personalized search results and Facebook's personalized news stream. According to Eli Pariser, who coined the term, users get less exposure to conflicting viewpoints and are isolated intellectually in their own informational bubble. Pariser related an example in which one user searched Google for "BP" and got investment news about British Petroleum while another searcher got information about the Deepwater Horizon oil spill and that the two search results pages were "strikingly different".^[25][26][27] The bubble effect may have negative implications for civic discourse, according to Pariser.^[28]

Since this problem has been identified, competing search engines have emerged that seek to avoid this problem by not tracking or "bubbling" users.

Faith-based search engines

The global growth of the Internet and popularity of electronic contents in the Arab and Muslim World during the last decade has encouraged faith adherents, notably in the Middle East and Asian sub-continent, to "dream" of their own faith-based i.e. "Islamic" search engines or filtered search portals filters that would enable users to avoid accessing forbidden websites such as pornography and would only allow them to access sites that are compatible to the Islamic faith. Shortly before the Muslim only month of Ramadan, Halalgoogling, which collects results from other search engines like Google and Bing, was introduced to the world in July 2013 to present the halal results to its users,^[29] nearly two years after I’mHalal, another search engine initially (launched on September 2011) to serve Middle East Internet had to close its search service due to what its owner blamed on lack of funding.^[30]

While lack of investment and slow pace in technologies in the Muslim World as the main consumers or targeted end users has hindered progress and thwarted success of serious Islamic search engine, the spectacular failure of heavily invested Muslim lifestyle web projects like Muxlim, which received millions of dollars from investors like Rite Internet Ventures, has - according to I’mHalal shutdown notice - made almost laughable the idea that the next Facebook or Google can only come from the Middle East if you support your bright youth.^[31] Yet Muslim internet experts have been determining for years what is or is not allowed according to the "Law of Islam" and have been categorizing websites and such into being either "halal" or "haram". All the existing and past Islamic search engines are merely custom search indexed or monetized by web major search giants like Google, Yahoo and Bing with only certain filtering systems applied to ensure that their users can't access Haram sites, which include such sites as nudity, gay, gambling or anything that is deemed to be anti-Islamic.^[32]

Another religiously-oriented search engine is Jewogle, which is the Jewish version of Google and yet another is SeekFind.org, which is a Christian website that includes filters preventing users from seeing anything on the internet that attacks or degrades their faith.^[33]

See also

• Most popular Internet search engines
• Comparison of web search engines
• List of search engines
• Answer engine (question answering)
  • Quora
  • True Knowledge
  • Wolfram Alpha
• Google effect
• Internet Search Engines and Libraries
• Semantic Web
• Spell checker
• Web development tools

References

Further reading

• 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 (6740): 107–9. doi:10.1038/21987. PMID 10428673. 
• Bing Liu (2007), Web Data Mining: Exploring Hyperlinks, Contents and Usage Data. Springer,ISBN 3-540-37881-2
• Bar-Ilan, J. (2004). The use of Web search engines in information science research. ARIST, 38, 231-288.
• 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. 
• 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. doi:10.1002/1097-4571(2000)51:10<949::AID-ASI70>3.0.CO;2-5. 
• Xie, M. et al. (1998). "Quality dimensions of Internet search engines". Journal of Information Science 24 (5): 365–372. doi:10.1177/016555159802400509. 
• Information Retrieval: Implementing and Evaluating Search Engines. MIT Press. 2010. 

External links

Wikimedia Commons has media related to Internet search engines.

• Search Engines at DMOZ