Alexa Internet, Inc. is a subsidiary of Amazon.com. Alexa provides traffic data, global rankings and other information on 30 million websites world wide. Alexa operates by cooperation with its clientele, each of whom installs a toolbar on their web site that assists an "Alexa Site Audit".
An Alexa audit audit includes traffic statistics, and Alexa's global rankings are based upon assessment within their clientele.
According to Alexa, it was founded in 1996.