A search engine lists web pages on the Internet. This facilitates research by offering an immediate variety of applicable options. Possibly useful items on the results list include the source material or the electronic tools that a web site can provide, such as a dictionary, but the list itself, as a whole, can also indicate important information. However, discerning that information may require insight.

Search engine results can help editors retain (what is notable) or delete (what is not verifiable) source material, depending on their reliability. There is a high demand for reliability on Wikipedia. Discerning the reliability of the source material is an especially core skill for using the web, while the wiki itself only facilitates the creation of multiple drafts. As presentations and deletions progress, this variety of choices for input tend to produce the desired objective—a neutral viewpoint. Depending on the type of query and kind of search engine, this variety can open up to a single author.

Some search engine tests

  1. Popularity – See Google's trending tool below.
  2. Usage – Identify a term's notability. (See for example Google's ngram tool.)
  3. Genuineness – Identify a spurious hoax or an urban legend.
  4. Notability – Decide whether a page should be nominated for deletion.
  5. Existence – Discover what sources (including websites) actually exist for possible presentation.
  6. Information – Review the reliability of facts and citations.
  7. Names and terminology – Identify the names used for things (including alternative names and terminology).
  8. Copyrighting – Identify whether material is copied, and if so, check the licensing.

This page describes both these web search tests and the web search tools that can help develop Wikipedia, and it describes their biases and their limitations.

The advantages of a specific search engine can be distinguished by using a variety of common search engines. The distinct advantages of each are their user interface and, less obviously, their algorithms for compiling and searching their own indexes. Because a web crawler can be blocked—specific ones or just in general—different search engines can list different web sites, and there are more web sites available by URL than are indexed in any database.

The most common search engines are Google, Bing, and Yahoo. Specialized search engines exist for medicine, science, news and law amongst others. Several generalized search engines exist. These adapt your query to many search engines. See § Common search engines below. This page mostly uses Google instead of Bing or Yahoo, but aims for generality where it can. For example, it describes Google Groups (usenet groups), Google Scholar (academia), Google News, and Google Books.

Good-faith searching: a rule of thumb

If an unsourced addition to an article appears plausible, consider taking a moment to use a suitable search engine to find a reliable source before deciding whether to revert.

Search engine tests

Depending on the subject matter, and how carefully it is used, a search engine test can be very effective and helpful, or produce misleading or non-useful results. In most cases, a search engine test is a first-pass heuristic or "rule of thumb".

What a search test can do, and what it can't

A search engine can index pages and text which others have placed on the internet, just like a big index at the back of a book.

Search engines can:

Search engines cannot:

and search engines often will not:

A search engine test cannot help you avoid the work of interpreting your results and deciding what they really show. Appearance in an index alone is not usually proof of anything.

Search engine tests and Wikipedia policies


Search engine tests may return results that are fictitious, biased, hoaxes or similar. It is important to consider whether the information used derives from reliable sources before using or citing it. Less reliable sources may be unhelpful, or need their status and basis clarified, so that other readers gain a neutral and informed understanding to judge how reliable the sources are.


Google (and other search systems) do not aim for a neutral point of view. Wikipedia does. Google indexes self-created pages and media pages which do not have a neutrality policy. Wikipedia has a neutrality policy that is mandatory and applies to all articles, and all article-related editorial activity.

As such, Google is specifically not a source of neutral titles – only of popular ones. Neutrality is mandatory on Wikipedia (including deciding what things are called) even if not elsewhere, and specifically, neutrality trumps popularity.

(See WP:NPOV § Neutrality and Verifiability for information on balancing the policies on verifiability and neutrality, and WP:NPOV § Article naming on how articles should be named)


Raw "hit" (search result) count is a very crude measure of importance. Some unimportant subjects have many "hits", some notable ones have few or none, for reasons discussed further down this page.

Hit-count numbers alone can only rarely "prove" anything about notability, without further discussion of the type of hits, what's been searched for, how it was searched, and what interpretation to give the results. On the other hand, examining the types of hit arising [clarification needed] (or their lack) often does provide useful information related to notability.

Additionally, search engines do not disambiguate, and tend to match partial searches. (However, as described below, you can eliminate partial matches by quoting the phrase to be matched): While Madonna of the Rocks is certainly an encyclopedic and notable entry, it's not a pop culture icon. However, due to Madonna matching as a partial match, as well as other Madonna references not related to the painting, the results of a Google or Bing search result count will be disproportionate as compared to any equally notable Renaissance painting. To exclude partial matches when Googling for the phrase, quote the phrase to be matched as follows: "Madonna of the Rocks".

Using search engines

Search engine expressions (examples and tutorial)

This section explains some search expressions used in Google web search.[2] Similar approaches will work in many other search engines, and other Google searches, but always read their help pages for further information as search engines' capabilities and operation often differ. Note that if you are signed in to a Google account when searching on Google then this may affect the results that you get, based on your search history.[3] Also be sure to check "Languages for Displaying (Search) Results" in "Search Settings".[4])

The single most useful search engine tool may be the use of quotation marks to find an exact match for a phrase. However, a search engine such as Google has both an easy, and an advanced search with further search options. The advanced search makes it easier to enter advanced options, that may help your searching. The following collapsible sections cover basic examples and help for using search engines with Wikipedia.

Specialized search engines such as medical paper archives have their own specialized search structure not covered here.

Specific uses of search engines in Wikipedia

Interpreting results


A raw hit count should never be relied upon to prove notability. Attention should instead be paid to what (the books, news articles, scholarly articles, and web pages) is found, and whether they actually do demonstrate notability or non-notability, case by case. Hit counts have always been, and very likely always will remain, an extremely erroneous tool for measuring notability, and should not be considered either definitive or conclusive. A manageable sample of results found should be opened individually and read, to actually verify their relevance.

In the case of Google (and other search engines such as Bing and Yahoo!), the hit count at the top of the page is unreliable and should usually not be reported. The hit count reported on the penultimate (second-to-last) page of results may be slightly more accurate. For searches with few reported hits (less than 1000) the actual count of hits needed to reach the bottom of the last page of results may be more accurate, but even this is not a sure thing. Google returns different search results depending on factors such as your previous search history and on which Google server you happen to hit.[8][9]

Other useful considerations in interpreting results are:

Biases to be aware of

In most cases, search results should be reviewed with an awareness and careful skepticism before relying upon them. Common biases include:

General biases

General (the Internet or people as a whole):

General web search engines (Google, Bing web search etc.):


Foreign languages, non-Latin scripts, and old names

Often for items of non-English origin, or in non-Latin scripts, a considerably larger number of hits result from searching in the correct script or for various transcriptions—be sure to check "Languages for Displaying (Search) Results" in "Search Settings".[4] An Arabic name, for instance, needs to be searched for in the original script, which is easily done with Google (provided one knows what to search for), but problems may arise if – for example – English, French and German webpages transcribe the name using different conventions. Even for English-only webpages there may be many variants of the same Arabic or Russian name. Personal names in other languages (Russian, Anglo-Saxon) may have to be searched for both including and excluding the patronymic, and searches for names and other words in strongly inflected languages should take into account that arriving at the total number of hits may require searching for forms with varying case-endings or other grammatical variations not obvious for someone who does not know the language. Names from many cultures are traditionally given together with titles that are considered part of the name, but may also be omitted (as in Gazi Mustafa Kemal Pasha).

Even in Old English, the spelling and rendering of older names may allow dozens of variations for the same person. A simplistic search for one particular variant may underrepresent the web presence by an order of magnitude.

A search like this requires a certain linguistic competence which not every individual Wikipedian possesses, but the Wikipedia community as a whole includes many bilingual and multilingual people and it is important for nominators and voters on AfD at least to be aware of their own limitations and not make untoward assumptions when language or transcription bias may be a factor.

Google distinct page count issues

Note also, that the number of search string matches reported by search engines is only an estimate. For example, Google will only calculate the actual number of matches once the user navigates through all result pages, to the last one, and even then it places restrictions on the figure. At times, the "match" count estimate can be significantly different (by one or more orders of magnitude) to the total count of results shown on the last results page.

A site-specific search may help determine if most of the matches are coming from the same web site; a single web site can account for hundreds of thousands of hits.

For search terms that return many results, Google uses a process that eliminates results which are "very similar" to other results listed, both by disregarding pages with substantially similar content and by limiting the number of pages that can be returned from any given domain. For example, a search on "Taco Bell" will give only a couple of pages from tacobell.com even though many in that domain will certainly match. Further, Google's list of distinct results is constructed by first selecting the top 1000 results and then eliminating duplicates without replacements. Hence the list of distinct results will always contain fewer than 1000 results regardless of how many webpages actually matched the search terms. For example, as of 14 December 2010, from the about 742 million pages related to "Microsoft", Google was returning 572 "distinct" results.[10]. Caution must be used in judging the relative importance of websites yielding well over 1000 search results.

Search engine limitations – technical notes

Many, probably most, of the publicly available web pages in existence are not indexed. Each search engine captures a different percentage of the total. Nobody can tell exactly what portion is captured.

The estimated size of the World Wide Web is at least 11.5 billion pages,[11] but a much deeper (and larger) Web, estimated at over 3 trillion pages, exists within databases whose contents the search engines do not index. These dynamic web pages are formatted by a Web server when a user requests them and as such cannot be indexed by conventional search engines. The United States Patent and Trademark Office website is an example; although a search engine can find its main page, one can only search its database of individual patents by entering queries into the site itself.[12]

Google, like all Internet search engines can only find information that has actually been made available on the Internet. There is still a sizable amount of information that is not on the Internet.

Google, like all major Web search services, follows the robots.txt protocol and can be blocked by sites that do not wish their content to be indexed or cached by Google. Sites that contain large amounts of copyrighted content (Image galleries, subscription newspapers, webcomics, movies, video, help desks), usually involving membership, will block Google and other search engines. Other sites may also block Google due to the stress or bandwidth concerns on the server hosting the content.

Search engines also might not be able to read links or metadata that normally requires a browser plugin, Adobe PDF, or Macromedia Flash, or where a website is displayed as part of an image. Search engines also can not listen to podcasts or other audio streams, or even video mentioning a search term. Similarly, search engines cannot read PDF files consisting of photoscans or look inside compressed (.zip) files.

Forums, membership-only and subscription-only sites (since Googlebot does not sign up for site access) and sites that cycle their content are not cached or indexed by any search engine. With more sites moving to AJAX/Web 2.0 designs, this limitation will become more prevalent as search engines only simulate following the links on a web page. AJAX page setups (like Google Maps) dynamically return data based on real-time manipulation of JavaScript.

Google has also been the victim of redirection exploits that may cause it to return more results for a specific search term than exist actual content pages.

Google and other popular search engines are also a target for search engine "search result enhancement", also known as search engine optimizers, so there may also be many results returned that lead to a page that only serves as an advertisement. Sometimes pages contain hundreds of keywords designed specifically to attract search engine users to that page, but in fact serve an advertisement instead of a page with content related to the keyword.

Hit counts reported by Google are only estimates, which in some cases have been shown to necessarily be off by nearly an order of magnitude, especially for hit counts above a few thousands.[13][14] For such common words as to yield several thousand Google hits, freely available text corpora such as the British National Corpus (for British English) and the Corpus of Contemporary American English (for American English) can provide a more accurate estimate of the relative frequencies of two words.

Example of the limitations

The Economic Crime Summit site is a rather Google- and Internet Archive-unfriendly site. It is very graphics heavy, providing Google with little to nothing to look for and many missing pages in the Internet Archive version. So while you can bring up the 2002 Economic Crime Summit Conference, the overview link that would tell you who presented what does not work. The 2004 Economic Crime Summit Conference archive is even worse as that was in three places and none of the archived links tells you anything about the papers presented.

Via Internet Archive you have proof that some information regarding "Impact of Advances in Computer Technology in Evidence Processing" existed on the Internet.[15] Yet today Google cannot find that information! A program known to be part of the 2002 Economic Crime Summit Conference and at one time was listed on a website on the Internet currently[when?] cannot be found by Google.

Common search engines

See also: List of search engines

The most common search engines are Google, Bing, Yahoo, and DuckDuckGo but the most useful search engine, which depend on a context, may not be the most common ones.

Type Examples
General search engines Google, Bing, Yahoo!, DuckDuckGo etc.
Professional research indexes Medline (medical), science, law, Google Scholar
News and media Google News
Historical archives of web pages Archive.org, Search engine caches (how web pages looked and their contents, at different times or if deleted)
Books and historical literature Project Gutenberg, Google Books and Amazon.com
Universities and higher education organisations 4icu.org (University websites search engine)

Specialized search engines

Google Scholar works well for fields that are paper-oriented and have an online presence in all (or nearly all) respected venues. This search engine is a good complement for the commercially available Thompson ISI Web of Knowledge, especially in the areas which are not well covered in the latter, including books, conference papers, non-American journals, the general journals in the field of strategy, management, international business,[16] English language education and educational technology.[17] The analysis of the PageRank algorithm utilised by Google Scholar demonstrated that this search engine, as well as its commercial analogs, provides an adequate information about popularity of some concrete source,[18] although that does not automatically reflect the real scientific contribution of concrete publication.[18]

MedLine, now part of PubMed, is the original broadly based search engine, originating over four decades ago and indexing even earlier papers. Thus, especially in biology and medicine, PubMed "associated articles" is a Google Scholar proxy for older papers with no on-line presence. E.g., The journal Stroke puts papers on-line back through 1970s. For this 1978 paper [1], Google Scholar lists 100 citing articles, while PubMed lists 89 associated articles

There are a large number of law libraries online, in many countries, including: Library of Congress, Library of Congress (THOMAS), Indiana Supreme Court, FindLaw (US); Kent University Law Library and sources (UK).

See also this list of search engines.

Generalized search engines

Several generalized search engines exist. These adapt your query to many search engines. Web browsers offer a choice of search engines to choose to employ for the search box, and these can be used one at a time to experiment with search results. Meta-search engines use several search engines at once. A web browser plugin can add a search engine or a meta-search engine to your list of choices.

See also


  1. ^ For example, if there are 16 hits at Google Books under one name, and 24 under another, there is only a 70% confidence that the second name is actually more common.
  2. ^ Google Search Operators and more search help
  3. ^ Search history personalization
  4. ^ a b Google Search Settings
  5. ^ Avoid inauthor:"Books, LLC", as LLC 'publishes' raw printouts of Wikipedia articles.
  6. ^ Google search for: AYB OR AYBABTU OR "All your base"
  7. ^ Google Answers question on word frequency in news sources
  8. ^ Takuya, Funahashi; Hayato, Yamana (2010). "Reliability Verification of Search Engines' Hit Counts" (PDF). Proceedings of the 10th international conference on Current trends in web engineering. Computer Science and Engineering Division, Waseda University. Retrieved 5 May 2015.
  9. ^ Sullivan, Danny (21 October 2010). "Why Google Can't Count Results Properly". SearchEngineLand.com. Retrieved 5 May 2015.
  10. ^ Google search for "Microsoft"
  11. ^ Gulli, Antonio; Signorini, Alessio (28 August 2005). "The Indexable Web is more than 11.5 billion pages". ((cite journal)): Cite journal requires |journal= (help)
  12. ^ More, Alvin; Murray, Brian H. (2000). "Sizing the Internet". Cyveillance. ((cite journal)): Cite journal requires |journal= (help)
  13. ^ Mark Liberman (2009), "Quotes with and without quotes", Language Log.
  14. ^ Liberman, Mark (2005), "Questioning reality", Language Log; and other Language Log posts linked from there.
  15. ^ http://web.archive.org/web/20011212161658/http://www.summit.nw3c.org/Programs_Agenda.htm
  16. ^ Harzing, A. W. K.; van der Wal, R. (2008). Google Scholar as a new source for citation analysis? Ethics in Science and Environmental Politics, vol. 8, no. 1, pp. 62–71
  17. ^ van Aalst, Jan. (2010) Using Google Scholar to Estimate the Impact of Journal Articles in Education. Educational Researcher 39: 387.
  18. ^ a b Maslov, S.; Redner, S. (2008). Promise and pitfalls of extending Google's PageRank algorithm to citation networks. Journal of Neuroscience, 28, 11103–11105

Further reading