google search engine

Google is a search engine owned by Google, Inc. whose mission statement is to "organize the world's information and make it universally accessible and useful". The largest search engine on the web, Google receives over 200 million queries each day through its various services.

The search engine

Index size

At its start in 1998, Google claimed to index 25 million web pages.^[1] By June 2005, this number had grown to 8 billion pages, as well as 17 million images, 1 billion Usenet messages, 6,600 print catalogs, and 4,500 news sources. Recently, Google claimed to index over 25 billion web pages and 1.3 billion images. After a controversy involving Yahoo's index size claims in summer of 2005, the number of indexed pages was removed from the Google home page.^[2]

Physical structure

Main article: Google platform

Google employs data centers full of low-cost commodity computers running a custom Red Hat Linux in several locations around the world to respond to search requests and to index the web. The server farms in the data centers are built using a shared nothing architecture. The indexing is performed by a program named Googlebot, which periodically requests new copies of 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 internal database of the web. This index database and web page cache is several terabytes in size. Google has developed its own file system called Google File System for storing all this data.

PageRank

Main article: PageRank

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.

Search Results

Google not only indexes and caches HTML files but also 13 other file types, which include PDF, Word documents, Excel spreadsheets, Flash SWF, plain text files, among others. Except in the case of text and SWF files, the cached version is a conversion to HTML, allowing those without the corresponding viewer application to read the file.

Users can customize the search engine somewhat. They can set a default language, use "SafeSearch" filtering technology (which is on 'moderate' setting by default), 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 32 first keywords are taken into account), 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.

Google optimization

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 tags, H1 heading tags and image alt attributes) and "off page" 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 tag and the body copy (note: the higher up in the page, 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.

One "off page" technique that works particularly well is Google bombing in which websites link to another site using a particular phrase in the anchor text, in order to give the site a high ranking when the word is searched for.

Google publishes a set of guidelines for a website's owners who would like to raise their rankings when using legitimate optimization consultants.^[3]

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 judgement, it does improve the ability of non-native translators to use more idiomatically correct English expressions.

Google dance

Previously, Google would update its index on a monthly basis, leading to suddenly fluctuating and unexpected results as its various servers were updated. This is no longer the case, because Google updates its index continuously as it crawls the web.

Search engine features

Besides the main search engine feature of searching for text, the search engine can be used as a mathematical problems solver, currency converter, dictionary and many others as well. These built-in search engine features are one of the reasons for the growing popularity of Google.

Search products

Main article: List of Google services and tools

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, 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, Froogle, Google Maps 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 include search features; Google Browser Sync doesn't offer any search facilties, although it aims to organise your browsing time.

Google jargon

To google 

to search something using google (also, to seek information on someone by entering their full name or other information)

Googler 

a person who uses Google's features very efficiently. Mostly uses the "I'm feeling lucky" button when searching. Fan of a google. 'Googler' is sometimes also used for "Expert Online Searcher". Also, a company term for a full-time google employee.

Nigritude ultramarine, SERPs, Seraphim Proudleduck, Mangeur de cigogne 

SEO competitions

Googledork 

A person who accidentally exposes information to the web by placing it into a location spidered by Google.

Google-proof 

Search-phrase delivering exactly the intended result while searching with Google.

Sandbox Effect 

The industry created name for a phenomenon that began in March 2004 in which Google seemingly filtered (from its results) any newly created websites. This was done to combat and filter search spam in which spammers were creating multitudes of sites for nefarious internet marketing purposes. Google reasoned that a valid site would progressively gain a natural link and content structure over time, and until the site could meet this 'trust threshold', it would be exempt from all but obscure search results.

Google bomb 

An attempt to influence the ranking of a given site in results returned by the Google search engine. Accomplished by linking many sites to the target site with 'bomb' keywords used as the link text. Notable Google bombs: google search for miserable failure. ('Bomb' keywords are 'miserable failure'.) 'Bomb' refers to the effect of having massive amounts of links created for the sole purpose of increasing the rankings of a 'target' website for the bomb keywords. Slang: "We Google bombed George Bush's web site with 'miserable failure'. Also known as Google wash.

Googlewhack 

A search using two dictionary-valid (underlined by Google) words that only results in one hit.

Google games

• In Gwigle, you learn advanced Google search tricks as you go through the puzzles.
• In Googlewhack you attempt to find two words that produce exactly one search result.
• In Google talk (not to be confused with Google Talk, Google's VoIP/IM service), google searches are used to complete a beginning of a sentence with words, leading to amusing or interesting results.
• In Googlefight, you pit two keywords against each other to find which one has more results.
• In Guess The Google, you attempt to guess which search term resulted in the displayed images.
• In Toogle, you can search images with the text of the search item making up the image. "The most comprehensive image buggery on the web"

See also

• elgooG
• Googlewhack
• History of Google
• Peter Norvig
• List of Google services and tools
• List of search engines
• MSN Search
• Yahoo! Search
• Ask Search

References

Further reading

• Google Hacks from O'Reilly is a book containing tips about using Google effectively. Now in its second edition. ISBN 0-596-00857-0
• 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

External links

• Google website
• Open Directory Project: Google
• Original google.stanford.edu (May 1998)
• Google Advanced Search Tips
• Google UK