Alexa Internet

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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. Alexa collects information from users who have installed an Alexa Toolbar, allowing them to provide statistics on web site traffic, as well as lists of related links.

1 Operations and history
2 Alexa rank information and the Alexa Toolbar
3 See also
4 External links

[edit] Operations and history

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.

In 1999, Alexa was acquired by Amazon.com for about $250 million in Amazon stock.

The company's premises are in Building 37 of the Presidio of San Francisco.

Alexa began a partnership with Google in spring 2002, and with the Open Directory Project in January 2003. Windows Live Search replaced Google as a provider of search results in May 2006. In September 2006 they began using their own Search Platform to serve results. Today, Alexa is primarily a 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.

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. Uniquely, their Web Search Platform gives developer's access to their raw crawl data.

[edit] Alexa rank information and the Alexa Toolbar

Alexa ranks sites based on visits from users of its Alexa Toolbar for Internet Explorer, and from integrated sidebars in Mozilla and Netscape. A third-party extension for Mozilla Firefox called SearchStatus was made available in May 2006; it allows users of this browser to view Google and Alexa rankings of a visited site and thereby also affect Alexa rankings.

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 (e.g., a random sample of sufficient size), Alexa's ranking should be quite accurate (see Sampling). In reality, the not much is known about the sample and it may or may not have many sources of statistical bias. Alexa itself notes several examples (here and here)

Another concern connected here is that Alexa ratings are easily manipulated. Some webmasters claim that they can significantly improve the Alexa ranking of less popular sites by making them the default page, by exchanging web traffic with other webmasters, and by requiring their users to install the Alexa toolbar[1]; however, such claims are often anecdotal and are offered without statistics or other evidence. To the contrary, traffic patterns seen on Alexa often strongly correlate with other sources of data.

Several file upload services have top Alexa rankings because they required their non-US and non-European visitors to install the Alexa toolbar in order to use the site's services.

Alexa provides an important, useful, and, for most websites, also independent source of information about website traffic. It reports some share of the traffic created by Alexa toolbar users. Unfortunately, Alexa's rankings are often misinterpreted as an exact or approximate measure of popularity of web sites.