Google is a U.S.-based search engine on the World Wide Web owned by the Google Inc. (Nasdaq: GOOG). Being the largest search engine on the web, Google receives at least 200 million (2 × 108) search requests per day through its website and client websites, such as AOL.
In addition to webpages, Google also provides services for searching images, Usenet newsgroups, news sites, and items for sale online. As of June 2004, Google has indexed 4.28 billion (4.28 × 109) webpages, 880 million images and 845 million Usenet messages — a total of six billion (6 × 109) items. It also caches much of the content that it indexes.
"To google," as a verb, has come to mean "to search for something on Google"; because of Google's popularity (80 percent of all web users, perhaps) it has also generically come to mean "to search the web." Google officials have discouraged this usage of the company name, as it could lead to their name becoming a genericized trademark.
Google began as a research project in early 1996 by Larry Page and Sergey Brin, two Stanford, Ph.D. students who developed the theory that a search engine based on a mathematical analysis of the relationships between websites would produce better results than the basic techniques then in use. It was originally nicknamed BackRub because the system checked backlinks to estimate a site's importance.
Convinced that the pages with the most links to them from other highly relevant webpages must be the most relevant ones, Page and Brin decided to test their thesis as part of their studies, and laid the foundation for their search engine. They formally founded their company, Google Inc., on September 7, 1998 at a friend's garage in Menlo Park, California. In February 1999, the company moved into the somewhat notorious 165 University Ave., Palo Alto, California office location, before moving to the "Googleplex" later that year.
Google gained a following among Internet users for its simple, clean design and relevant search results. Advertisements were sold by the keyword so that they would be more relevant to the end user, and the ads were text-based in order to keep page design uncluttered and fast-loading.
In September 2001, Google's ranking mechanism (PageRank) was awarded a U.S. Patent. The patent was officially awarded to Leland Stanford University and lists Lawrence Page as the inventor.  (http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&p=1&u=/netahtml/search-bool.html&r=1&f=G&l=50&co1=AND&d=ptxt&s1=6,285,999.WKU.&OS=PN/6,285,999&RS=PN/6,285,999)
At its peak in early 2004, Google handled upwards of 80 percent of all search requests on the world wide web through its website and clients like Yahoo!, AOL, and CNN. (http://www.onestat.com/html/aboutus_pressbox21.html) Google's share fell in February 2004 when Yahoo! dropped Google's search technology in order to deliver independent results.
Google includes humorous features such as cartoon Modifications (http://www.google.com/holidaylogos.html) of their logo for special occasions, the option to display the site in fictional or humorous languages such as Klingon and Leet, and April Fool's Day jokes about the company.
It is conjectured that Google's future is personalized searches, using the data that gathered from Orkut, Gmail and Froogle to give results based on an individual's previous actions. In fact, there is a Personalized Google Search (http://labs.google.com/personalized)Beta in Google Labs (http://labs.google.com/), the experimental section of the site.
The name "Google" is a play on the word googol, which was coined by Milton Sirotta, nephew of U.S. mathematician Edward Kasner in 1938, to refer to the number represented by 1 followed by a hundred zeros. Google's use of the term reflects the company's mission to organize the immense amount of information available on the Web.
A number of organizations (most controversially the Church of Scientology) have used the Digital Millennium Copyright Act to demand that Google remove references to allegedly copyrighted material on other sites. Google typically handles this by removing the link as requested and including a link to the complaint in the search results. There have also been complaints that the "Google cache" feature violates copyright. However, the consensus seems to be that caching is a normal part of the functionality of the web, and that HTTP provides adequate mechanisms for requesting that caching be disabled (which Google respects; it also honors the robots.txt file which is a mechanism to allow the owners of a site to request that part or all of their site not be included in search engine listings).
In 2002, news reports surfaced that the Google search engine had been banned in China. A mirror site (in all respects, including mirrored text) called elgooG proved useful to get around the ban. The ban was later lifted, and reports indicated that it was not Google itself that was targeted. Rather, Google's feature of a cached version of a website would allow Chinese users to circumvent any ban of a website itself, merely by visiting the cache instead. There is also a dynamic Google mirror working as a proxy server at http://www.zensur.freerk.com/google/ .  (http://www.zensur.freerk.com/google/)
Google's efforts to refine its database has led to some legal controversy, drawing a lawsuit in October 2002 from a company, SearchKing, that sought to sell advertisements on pages with inflated Google rankings. In its defense, Google said that its rankings are its constitutionally protected opinions of the web sites that it lists. A judge threw out SearchKing's lawsuit in mid-2003 on precisely these grounds.
In late 2003 and early 2004, there were persistent rumors that Google would be sued by the SCO Group over its use of the Linux operating system, in conjunction with SCO's lawsuit against IBM over the ownership of intellectual property rights relating to Linux.
The search engine
Google employs server farms of Linux computers around the world to answer search requests and to index the web. The server farms are built using a shared nothing architecture. The indexing is performed by a program ("Googlebot") which periodically requests new copies of the web pages it already knows about. The more often a page updates, the more often Googlebot will visit. The links in these pages are examined to discover new pages to be added to its database. The index database and web page cache is several terabytes in size.
The exact size and whereabouts of the physical machines in the Google search engine are unknown, and official figures remain intentionally vague. According to John Hennessy and David Patterson's Computer Architecture: A Quantitative Approach, the server farm cluster forming the Google "search farm" would in the year 2000 have consisted of about 6000 processors, 12000 common IDE-disks (2 per machine, and one machine per processor), at four sites: two in Silicon Valley and two in Virginia.
Each site had an OC 48 (2488 Mbit/s, see broadband Internet access article) connection to the Internet and an OC 12 (622 Mbit/s) connections to other Google sites. The connections are routed through a Cisco 12000 network switch and split by two Foundry Networks BigIron 8000 Ethernet switches dividing the traffic onto 4 x 1 Gbit/s lines connecting up to 64 racks, with 40 machines and an HP Ethernet switch on both back and flip side, so that a rack would fit 80 machines and two HP switches.
Based on the Google IPO S-1 form released in April 2004, Tristan Louis, the Vice President of application development for the Internet unit of a large financial firm, estimated the current server farm to contain something like the following  (http://www.tnl.net/blog/entry/How_many_Google_machines):
According to this estimate, the Google server farm constitutes the most powerful supercomputer in the world, being able to perform at least three times as many calculations per second as the Earth Simulator.
PageRank and indexing
Google uses an algorithm called PageRank to rank web pages that match a given search string. The PageRank algorithm computes a recursive figure of merit for web pages, based on the weighted sum of the PageRanks of the pages linking to them. The PageRank thus derives from human-generated links, and correlates well with human concepts of importance. Previous keyword-based methods of ranking search results, used by many search engines that were once more popular than Google, would rank pages by how often the search terms occurred in the page, or how strongly associated the search terms were within each resulting page. In addition to PageRank, Google also uses other secret criteria for determining the ranking of pages on result lists.
Google not only indexes and caches HTML-files but also 12 other file types, including .PDF, .txt, .doc, and .xls. Except in the case of text files, the cached version is a conversion to HTML. Hence Google allows reading these files even without having the corresponding program such as Word or Excel.
Users can customize the search engine somewhat. They can set a default language, use "SafeSearch" filtering technology, and set the number of results shown on each page. Google has been criticized for placing long-term cookies on users' machines to store these preferences, a tactic which also enables them to track a user's search terms over time. For any query (of which only the 10 first keywords are taken into account), up to the first 1000 results can be shown with a maximum of 100 displayed per page.
Despite its immense index, there is also a considerable amount of data in databases which are accessible from websites by means of queries, but not by links. This so-called deep web is not covered by Google and contains e.g. catalogues of libraries, official legislative documents of governments, phone books, etc.
(For an April Fool's parody of PageRank, see Google's PigeonRank page (http://www.google.com/technology/pigeonrank.html))
"Google dance" and optimization
Since Google is the most popular search engine, many webmasters have become eager to follow and to explain changes to the rankings of their websites. A new industry of consultants has arisen to help websites raise their rankings on Google and on other search engines. This field, called search engine optimization, attempts to discern patterns in search engine listings, and then develop a methodology for increasing rankings.
One technique commonly used is Google bombing in which many sites link to another site through a particular word, in order to give the site a high ranking when the word is searched for.
Forums can be found on the web where phenomena such as the "Google dance" are discussed. The Google dance is a period of a few days towards the end of a month when Google updates its database and ranking algorithms. Changes to the database can be observed by examining the number of results to a particular page such as "link:www.yahoo.com".
During the dance period, a site's ranking may change dramatically over a short period of time and different Google servers (e.g., www.google.com, www2.google.com, www3.google.com, www.google.co.uk, www.google.com.au, etc.) may give different results for the same search. The dance period appears to coincide with the time at which the googlebot examines stable sites. Rapidly changing sites, highly ranked sites and news sites are examined more often, although apart from news. Only minor adjustments are made to rankings during most of the month. In some cases it may take two or three months before new pages appear in search results. The monthly searching, indexing and ranking cycle was replaced by a continuous rolling update in the summer of 2003. This change in the way Google updates significantly reduced the unstable results of the monthly update dance.
One of Google's chief challenges is that as its algorithms and results have gained the trust of web users, the profit to be gained by a commercial web site in subverting those results has increased dramatically. Some search engine optimization firms have attempted to inflate specific Google rankings by various artifices, and thereby draw more searchers to their clients' sites. Google has managed to weaken some of these attempts by reducing the ranking of sites Google knows to use them.
Google publishes a set of guidelines (http://www.google.com/webmasters/guidelines.html) for a website's owners who would like to raise their rankings when using legitimate optimization consultants.
This is a service where Google will send you custom alerts based on its search technology.
In April 2002, Google launched a new service called "Google Answers". Google Answers is an extension to the conventional search — rather than doing the search themselves, users pay someone else to do the search. Customers ask questions, offer a price for an answer, and researchers answer them. Researchers are screened through an application process that tests their research and communications abilities. Prices for questions range from $2 to $200; Google keeps 25% of the payment, sends the rest to the researchers, and charges an additional $0.50 listing fee. Once a question is answered, it remains available for anyone to browse for free. This service came out of beta in May 2003 and presently receives more than one hundred question postings per day.
As of late August, 2004, Google's catalogs search feature is in the beta stage. Numerous (over 6,600 at the time of this writing) print catalogs are archived on Google as scanned image files. Through the use of character recognition, users can search for a text string in these catalogs in a fashion similar to how they would for materials on the general web. Matching results are displayed through thumbnails of the page(s) on which the text was found, with the specific area of the page where the search result is found shaded in a yellow box. Another image file next to the thumbnail, a shrinked version of the highlighted area on the thumbnail, highlights the exact location of the search result. Users can then access the page of the catalog (as a larger graphic file) and change pages by using a navigation bar positioned above the page image. It might be worth noting that one can access the catalogs without a search as well.
Google's database arranged into subcategories like an advanced Yellow Pages of the web.
In December 2003, Google announced Froogle, a spin-off that searches catalogues for particular products. This site had been active in beta for some months. It is now offered in Wireless Markup Language (WML) form and can be accessed from phones or other wireless devices that have support for WML.
Google maintains a usenet archive, called Google Groups (formerly an independent site known as DejaNews).
Google is currently testing a new version of its Groups service, which archives mailing lists in addition to usenet posts, using the same interface as Gmail (see below).
Google Images is an image search function. The latter is based on the text on the page adjacent to the image, the image caption, etc. A small version of the images is cached to comply with fair use laws.
All of Google's experimental technologies. Located at labs.google.com, Google Labs is akin to a directory page that links to all Google technologies under development or in beta that have not yet been made widely available. From the Google Labs home page, a user can access Google Groups 2 Beta, Google Compute, and other web technologies.
Allows users to search for results within a set location.
Google introduced a beta release of an automated news compilation service, "Google News" in April 2002. There are different versions of the aggregator for the languages English, German, French, Spanish, and Italian. To quell any charges of reporting bias, it is fully automated with no human editors.
The service covers the news articles that appeared within the past 30 days on news websites in the language concerned, from various countries; for the English language it covers about 4,500 sites, for the other languages less. It provides around the first 200 characters and links to the full article. Some of these websites require a subscription; in that case this is noted in the Google News summary of their articles.
Google News provides searching, and the choice of sorting the results by date and time of publishing (not to be confused with date and time of the news happening) or grouping them (and also grouping without searching). In the English version, there is an option to tailor the grouping to a selected national audience.
Users can request Google News Alerts on various topics by subscribing while using key words. An email is sent when a news article matching the request comes online.
The Google News services can also be customized for the country that you are from.
In August, 2004, Google released its new "Google Print" feature. This tool searches the contents of books submitted by publishers, and displays matches before the regular web matches. It offers links to purchase the book, as well as advertisements related to the content. Google will only allow users to view a limited number of pages from each book. In order to enforce these limits, they will track users of the system. As of early August, 2004, this service is still in beta. This feature is in response to the "Search inside this book" feature from A9.com.
Allows you to perform special searches such as U.S. Government Search, Linux Search, BSD Search, Apple Macintosh Search, and Microsoft Search.
Allows you to search certain University sites.
Google Browser Buttons
This tool allows you to put links to Google services in your web browser.
In December 2003, Google launched the beta version of the Google Deskbar, a search tool which runs from the Microsoft Windows taskbar, without a browser having to be open. It can return film reviews, stock quotes, dictionary and thesaurus definitions, plus any pre-configured search of a third-party site (e.g. eBay or Amazon).
Google Desktop Search
Formally known under the codename Puffin, Google Desktop Search runs locally on a PC and will index all Microsoft Outlook & Outlook Express emails, text documents, Microsoft Office documents, AOL Instant Messenger conversations and the Internet Explorer history on that PC and allow the user to search them from a browser. Google Desktop Search is an extension of Google Search. After indexing your files, your local results will turn up on normal Google search on your local computer.
Google Desktop Search does not store your files on the web and your personal information is not sent to Google.
Google Desktop Search was likely developed in response to file and Web search capabilities that will be offered in the next major release of Microsoft Windows, codenamed Longhorn (slated for release in 2006) — features that directly compete with Google's core Internet search business.
Currently, the beta version of Google Desktop Search does not support Google's "Did You Mean" feature. If you let it look up your computer for "chicke," it will not ask did you mean "chicken?"
Google Language Tool
This tool allows you to use Google in many different languages.
This addition to Microsoft Internet Explorer 5 or later adds Google's searching capabilities in a toolbar in the browser. The latest version includes pop-up ads blocking, automatic filling of forms, and the ability to show the Google PageRank value for the current page being viewed. It has been criticized for being a security risk because it updates itself without user intervention.
Other browsers, such as Mozilla Firefox, Opera and Safari, have built-in search tools that offer the same functionality. Mozilla Firefox also has its own version of the Google Toolbar, the Googlebar, which is developed independently of and is not supported by Google or the Mozilla Firefox developers. It expands upon the official google toolbar to the point that the only feature not replicated is the Google PageRank functionality. Google has also been built into Safari for Apple Computer's new OS X operating system.
Google Translate Tool
This tool allows you to translate pages and text into other languages.
Google Web API
The Google Web API (or Google Web Services) is Google's public interface for registered developers. Using Simple Object Access Protocol (SOAP), a programmer can write services for search and data-mining that rely on Google's results. Also, websurfers can view cached pages and make suggestions for better spelling.
By default a developer has a limit of 1,000 requests per day. This program is still in Beta phase. Google is one of the few search engines to make its results available via a public API; Technorati is another good example. Some popular implementations of the Google Web API include the alerting service Google Alert, or FindForward (http://www.findforward.com), as well as the Google Dance Tool, which monitors when Google is spidering the Internet.
Criticism of Google
While Google's apparent effectiveness has led droves of people to use it as their primary search tool, Google has managed to become the target of critics as well. Online journalists disliked that Google News equated press releases with news articles. In February 2003, Google banned the ads of Oceana, a two and a half year old non-profit group, which was protesting over a major cruise line's sewage treatment methods. Chris Hoofnagle, associate director of the Electronic Privacy Information Center in Washington, DC warned that "As courts become more frequent integrators of electronic records, there is a greater risk of Google ... becoming a serious privacy threat."
Claims of partiality
In April 2004, Google received complaints about the way that a search for "Jew" on its site listed the anti-Jewish website Jew Watch at or towards the top of the list. Google insisted this was a result of their content-neutral algorithm responding to the high PageRank of the Jew Watch website (http://www.google.com/explanation.html). A Google bomb was employed to place AskFactMaster.Com's entry, Jew, at the top. Jew Watch was also highly ranked in other search engines, such as Yahoo! and MSN, but those companies apparently received little or no criticism.
Jew Watch's main page was dropped from Google's results at the end of April because Jew Watch's web hosting service EV1 cancelled its account, and the site was inaccessible for several days. Since Google's webcrawler could not reach the site after repeated attempts, the main page was dropped from Google's index.  (http://news.com.com/2100-1038_3-5200203.html) The site later found another hosting service and was re-indexed by Google during the first week of May. Google explains that "The only sites we omit are those we are legally compelled to remove," in its disclaimer "Offensive Search Results" of April 23, 2004.
Claims of censorship
Sites advocating race as a virtue or historical revisionism have been banned for years in the French and German Googles, as such speech is illegal in those countries. The Chinese version of Google restricts searches on tens of thousands of keywords, acting as a technological partner to the content control policies of the Chinese central government (http://www.weeklystandard.com/Content/Public/Articles/000/000/004/699bevot.asp). Other potentially controversial sites such as hardcore pornographic sites have remained almost unaffected, however (only suppressed by a default "moderate SafeSearch" filter). Apparently, the US government has applied pressure on Google: image searches are filtered by Google. For example, searching for Lynndie England in the image search engine returns zero images  (http://images.google.com/images?hl=en&lr=&safe=off&q=Lynndie+England).
Claims of privacy invasion
It has been claimed that Google infringes the privacy of visitors by uniquely identifying them using cookies. It is claimed the cookies possess excessively distant expiry dates and that users' searches are recorded without permission for advertising purposes. In their defense Google claim cookies are necessary to maintain user preferences between sessions and the website otherwise functions normally if the user turns down the cookies.
Some users believe the processing of email message content by Google's GMail service goes beyond proper use. The point is often made that people without GMail accounts, who have not agreed to the GMail terms of service, but send email to GMail users have their correspondence analyzed without permission. Google claims that mail sent to or from GMail is never read by a human being, and is only used to improve relevance of advertizements.
Criticisms of PageRank system
Google's central PageRank system has been criticized, some calling it 'undemocratic'. Common arguments by Google's detractors are that the system is unfairly biased towards large sites, and that the criteria for a page's importance are not subject to peer review.
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