Alexa Internet

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Image:Alexa compact logo.gif Alexa Internet is a California-based subsidiary company of Amazon.com, that is best known for operating a website (www.alexa.com) that provides information on the web traffic to other websites. Its premises are in Building 37 of the Presidio of San Francisco.

Founded in 1996 by Brewster Kahle and Bruce Gilliat and backed by Jacqui Safra's Etoile Investments as a commercial offshoot of the Internet Archive, Alexa Internet created related links derived from user behavior (a form of collaborative filtering) for users of the Internet Explorer and Netscape Navigator web browsers. Engineers at Alexa created the Internet Archive's Wayback Machine. Alexa also supplies the Internet Archive with web crawls. It should be noted that Alexa only works with a Windows/Internet Explorer 5.0 or newer combination[1], and so does not collect information on Apple and Linux users, or those PC users of Mozilla Firefox, Opera, or other PC browsers, or mobile phone WAP or WWW users, or PDA users.

Alexa collects information on Web usage through the Windows-only application, the Alexa Toolbar. This allows them to provide statistics on web site traffic, as well as related link information. The Alexa Toolbar has a bad reputation with anti-spyware programs, as it collects information on search habits.

In 1999, Alexa was acquired by Amazon.com for about $250 million in Amazon stock. The "site info" link on the Alexa site lists related links for websites and also records how much web traffic they receive. Alexa began a partnership with Google in spring 2002, and with the Open Directory Project in January 2003. Today, Alexa is primarily a Google-based search engine, an Open Directory-based web directory, and a supplier of site information.

Alexa also provides "site info" for the A9.com search engine and for Alexadex.com.

In December 2005, Alexa opened its extensive search index and web-crawling facilities to third party programs through a comprehensive set of web services and APIs. These could be used for instance to construct vertical search engines that could run on Alexa's own servers or elsewhere.

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Alexa Rank Information

Alexa ranks sites based on the use of the Alexa Toolbar which is only available for Internet Explorer. There is some controversy over how representative Alexa's user base is of typical internet behavior. If Alexa's user base is a fair statistical sample of the internet user population, then Alexa's ranking would be accurate, but if the user base had a strong statistical bias, then these biases would skew the results.

Alexa themselves admit several sources of bias - for instance, sites with relatively low traffic will not be accurately ranked, nor sites with a disproportionate amount of users who use non-IE browsers; and subdomains are included in the main domain's rank/trend figures. [2]

In practice, due to Alexa's sample size, perceived usefulness, and availability, many news organizations, site owners, and even investors use Alexa's rankings to determine the popularity of web sites.

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