Alexa’s traffic estimates and ranks are based on a sample of millions of Internet users

Alexa’s Traffic Ranks are based on the traffic data provided by Alexa’s global sample over a rolling 3 month period. Traffic Ranks are updated daily. A site’s ranking is based on a combined measure of Unique Visitors and Pageviews. Unique Visitors are determined by the number of unique Alexa users who visit a site on a given day. Pageviews are the total number of Alexa user URL requests for a site. However, multiple requests for the same URL on the same day by the same user are counted as a single Pageview. The site with the highest combination of unique visitors and pageviews is ranked #1.