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|Headquarters||San Francisco, California, USA|
|Industry||Internet information providers|
|Type of site||Web traffic and ranking|
|Advertising||Web banner with AdBrite|
Alexa Internet, Inc. is a California-based subsidiary company of Amazon.com that is known for its toolbar and website. Once installed, the toolbar collects data on browsing behavior which is transmitted to the website where it is stored and analyzed and is the basis for the company's web traffic reporting.
 Operations and history
Alexa Internet was founded in 1996 by Brewster Kahle and Bruce Gilliat. The company's name was chosen in homage to the Library of Alexandria, drawing a parallel between the largest repository of knowledge in the ancient world to the potential of the Internet.
The company offered a toolbar that gave Internet users suggestions on where to go next, based on the traffic patterns of its user community. Alexa also offered context for each site visited: to whom it was registered, how many pages it had, how many other sites pointed to it, and how frequently it was updated.
Alexa's operation includes archiving of webpages as they are crawled. This database served as the basis for the creation of the Internet Archive accessible through the Wayback Machine. In 1998 the company donated a copy of the archive, 2 terabytes in size, to the Library of Congress. Alexa continues to supply the Internet Archive with web crawls.
In 1999, Alexa was acquired by Amazon.com for about $250 million in Amazon stock as the company moved away from its original vision of providing an 'intelligent' search engine. Alexa began a partnership with Google in early 2002, and with the Open Directory Project in January 2003. In May 2006, Amazon replaced Google with Live Search as a provider of search results. In September 2006, they began using their own Search Platform[clarification needed] to serve results. In December 2006, they released Alexa Image Search. Built in-house, it is the first major application to be built on their Web Platform.
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. In May 2007, Alexa changed their API to require comparisons be limited to 3 sites, reduced size embedded graphs be shown using Flash, and mandatory embedded BritePic ads.
In April 2007, the lawsuit Alexa v. Hornbaker was filed to stop trademark infringement by the statsaholic service. In the lawsuit, Alexa alleged that Hornbaker was stealing traffic graphs for profit, and that the primary purpose of his site was to display graphs that were generated by Alexa's servers. Hornbaker removed the term Alexa from his service name on March 19, 2007. Nevertheless, Alexa expressly grants permission to refer its data in third-party work subject to suitable credits.
On November 27, 2008, Amazon announced that Alexa Web Search was no longer accepting new customers, and the service would be deprecated or discontinued for existing customers on January 26, 2009.
 Accuracy of ranking by the Alexa Toolbar
Alexa ranks sites based on tracking information of users of its Alexa Toolbar for Internet Explorer and from integrated sidebars in Firefox and Chrome. Hence the page is only ranked between users who have these sidebars installed and may be biased if specific audience is reluctant to do this (Windows Defender has classified the sidebar as malware while it assigns it to trojans). Also, the rank is based on three month data and takes a long time to reflect changes in content that may happen after the domain has been sold. Finally, low ranks cannot be accurate not just because of the lack of data but also because of statistic laws related to the long tail distribution.
There is some controversy over how representative Alexa's user base is of typical Internet behavior, especially for less trafficked sites. In 2007 Michael Arrington provided a few examples of relative Alexa ranking known to contradict data from comScore, including ranking YouTube ahead of Google.
On April 16, 2008, many users reported dramatic shifts in their Alexa rankings. Alexa confirmed this later in the day with an announcement that they had released the new Alexa ranking system, claiming that they now take into account more data sources "beyond Alexa Toolbar users".
 Redesign and new statistics
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On March 31, 2009, Alexa website underwent a complete redesign with new metrics including: Pageviews per each individual User, Bounce Rate, and User Time on Site. In the following weeks they added new features including Demographics, Clickstream and Search Traffic stats. These new features were introduced in order to compete with other services such as Compete.com and Quantcast.
Symantec classifies the toolbar as trackware. McAfee classifies it as adware, a "Potentially Unwanted Program." McAfee Site Advisor rates the Alexa website as "green" finding "no significant problems" albeit a "small fraction of downloads...that some people consider adware or other potentially unwanted programs."