Originally Posted by Killswitch

Alexa is based off users who have the Alexa toolbar installed. And it doesn't go by uniques, it goes by page views. That's why forums have high Alexa's even though they have low uniques.

A site with 100k visitors a day and 5 page views per user will have a higher Alexa than a site with 200k visitors a day and 2 page views per user.