Google search is a Web search engine owned by Google, Inc., and it is the most used search engine on the Web. Google receives several hundred million queries each day through its various services. Google search was originally developed by Larry Page and Sergey Brin
The domain google.com attracted at least 135 million U.S. visitors in May 2008.
The search engine
uses a patented
system called PageRank
to help rank web pages that match a given search string. The PageRank algorithm computes a recursive
score for web pages, based on the weighted sum of the PageRanks of the pages linking
to them. The PageRank derives from human-generated links, and is thought to correlate
well with human concepts of importance.
The exact percentage of the total of web pages that Google indexes
is not known, as it is very hard to actually calculate. 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, reported to be a number over 200.
Google not only indexes and caches web pages but also takes "snapshots" of other file types, which include PDF, Word documents, Excel spreadsheets, Flash SWF, plain text files and much more. Except in the case of text and SWF files, the cached version is a conversion to (X)HTML, allowing those without the corresponding viewer application to read the file.
Users can customize the search engine, by setting a default language, using the "SafeSearch" filtering technology and set the number of results shown on each page. Google has been criticized for placing long-term [cookie|cookies] on users' machines to store these preferences, a tactic which also enables them to track a user's search terms and retain the data for more than a year. For any query, up to the first 1000 results can be shown with a maximum of 100 displayed per page.
Non-web sources of data
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 minimally covered by Google and contains, for example, catalogs of libraries, official legislative documents of governments, phone books, and more.
Since Google is the most popular search engine, many webmasters
have become eager to influence their website's Google rankings. An 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 improving rankings.
As Google's algorithms and results have gained the trust of web users, commercial websites will profit from subverting these results by artificially inflating their rankings. Some search engine optimization firms have attempted to inflate specific Google rankings by various artifices, and thereby draw more searchers to their client's sites. One of Google's main challenges has been to weaken some of these attempts by reducing the ranking of sites known to use them.
Search engine optimization encompasses both "on page" factors (like body copy, title elements, H1 heading elements and image alt attribute values) and Off Page Optimization factors (like anchor text and PageRank). The general idea is to affect Google's relevance algorithm by incorporating the keywords being targeted in various places "on page", in particular the title element and the body copy (note: the higher up in the page, presumably the better its keyword prominence and thus the ranking). Too many occurrences of the keyword, however, cause the page to look suspect to Google's spam checking algorithms.
The Google webmaster guidelines were published for website owners who would like to raise their rankings when using legitimate optimization consultants.
Uses of Google
A corollary use of Google—and other Internet search engines
—is that it can help translators to determine the most common way of expressing ideas in the English language (and other languages). This is generally done by doing a 'count' of different variants, thereby establishing which expression is more common. While this approach requires careful judgment, it does improve the ability of non-native translators to use more idiomatically
correct English expressions.
Google dance refers to the period of time when Google indices are tuned. This will often cause both a fluctuation in index size as well a significant change in a web site's search result position.
"Google Dance" also refers to the annual party at the Googleplex during the Search Engine Strategies San Jose conferences.
The Google search engine has many intuitive features making it more functional. This could have played a role in making it as popular as it is today. Google is one of the top ten most-visited websites today. Some of its features include a definition link for most searches including dictionary words, a list of how many results you got on your search, links to other searches (e.g. you misspelled something, it gives you a link to the search results had you typed in the correct search), and many more. It is unknown whether functionality, speed, or luck brought it its peak status.
Google's search engine normally accepts queries as a simple text area, and breaks up the user's text into a sequence of search terms, which will usually be words that are to occur in the results, but may also be phrases, delimited by quotations marks ("), qualified terms, with a prefix such as "+", "-", or one of several advanced operators, such as "site:". The Google Help Pages
document all of these additional queries.
Google's Advanced Search web form gives several additional fields which may be used to qualify searches by such criteria as date of first retrieval. All advanced queries transform to regular queries, usually with additional qualified terms.
Google applies query expansion
to the submitted search query, transforming it into the query that will actually be used to retrieve results. As with page ranking, the exact details of the algorithm Google uses are deliberately obscure, but certainly the following transformations are among those that occur:
- Term reordering: in information retrieval this is a standard technique to reduce the work involved in retrieving results. This transformation is invisible to the user, since the results ordering uses the original query order to determine relevance;
- Stemming is used to increase search quality by keeping small syntactic variants of search terms ;
- There is a limited facility to fix possible misspellings in queries.
"I'm Feeling Lucky"
Google's homepage includes a button labeled "I'm Feeling Lucky". When a user clicks on the button the user will be taken directly to the first search result, bypassing the search engine results page
. The thought is that, if a user is "feeling lucky", the search engine will return the perfect match the first time without having to page through the search results.
According to a study by Tom Chavez of "Rapt", this feature costs Google $110 million a year as 1% of all searches use this feature and bypass all advertising.
Search engine features
Besides the main search engine feature of searching for text, the search engine can also be used as a calculator, base, unit and currency converter, dictionary and many other useful tools.
Some searches will give a 403 Forbidden error with the text
... but your query looks similar to automated requests from a computer virus or spyware application. To protect our users, we can't process your request right now.
We'll restore your access as quickly as possible, so try again soon. In the meantime, if you suspect that your computer or network has been infected, you might want to run a virus checker or spyware remover to make sure that your systems are free of viruses and other spurious software.
We apologize for the inconvenience, and hope we'll see you again on Google."
followed by a CAPTCHA
The screen was first reported in 2005, and was a response to the heavy use of Google by search engine optimization companies to check on ranks of sites they were optimizing. The message may also be triggered by high volumes of different searches from a single IP address. The block is removed after a day.
Google is available in many languages and has been localized for many countries.
The interface has also been made available in some languages for humorous purpose:
In addition to the main URL Google.com
, Google owns 160 domain names for each of the countries/regions in which it has been localized. As Google is an American company, the main domain name can be considered as the U.S. one though the gTLD .com
can be used by any company in the world (not only those from the United States). Google.us does exist but is only a redirection
to google.com because dot-US
is by far less common than dot-com
in the United States. An example is Google.ca
Some domain names unregistered by Google are currently squatted
- Google.ua (Ukraine), the correct URL is google.com.ua
- Google.by (Belarus), the correct URL is google.com.by
- Google.cm (Cameroon), common mis-typing of google.com (there is no localized version for Cameroon)
- googol.com, the correct spelling of the number one googol, or 10^100, to which the name Google is a reference.
In addition to its tool for searching webpages, Google also provides services for searching images, Usenet newsgroups, news websites, videos, searching by locality, maps, and items for sale online. In 2006, Google has indexed over 25 billion web pages, 400 million queries per day, 1.3 billion images, and over one billion Usenet messages. It also caches much of the content that it indexes. Google operates other tools and services including Google News, Google Suggest, Google Product Search, Google Maps, Google Co-op and Google Desktop Search.
There are also products available from Google that are not directly search-related. Gmail, for example, is a webmail application, but still includes search features; Google Browser Sync does not offer any search facilities, although it aims to organize your browsing time.
- Google Hacks from O'Reilly is a book containing tips about using Google effectively. Now in its third edition. ISBN 0-596-52706-3.
- Google: The Missing Manual by Sarah Milstein and Rael Dornfest (O'Reilly, 2004). ISBN 0-596-00613-6
- How to Do Everything with Google by Fritz Schneider, Nancy Blachman, and Eric Fredricksen (McGraw-Hill Osborne Media, 2003). ISBN 0-07-223174-2
- Google Power by Chris Sherman (McGraw-Hill Osborne Media, 2005). ISBN 0-07-225787-3
- SEO for Google by Paul Bliss - an eBook that describes in precise detail the methods needed to get your site top rankings in Google for your keywords.
- Barroso, Luiz Andre; Dean, Jeffrey; Hölzle, Urs (2003). "Web Search for a Planet: The Google Cluster Architecture". IEEE micro 23 (2): 22–28.