What is Alexa Ranking?
This is a ranking system set by alexa.com (a subsidiary of amazon.com) that basically audits and makes public the frequency of visits on various Web sites. The algorithm according to which Alexa ranking traffic is calculated, is simple. It is based on the amount of traffic recorded from users that have the Alexa toolbar installed over a period of three months.
This website traffic is based on such parameters as reach and page views. The reach refers to the number of Alexa users who visit a particular site in one day. Page view, as its name shows, is the number of times a particular page (URL) is viewed by Alexa users. Alexa.com makes it clear though that, if a particular user visits the same URL multiple times on the same day, all those visits will be counted as one.
The first step of the ranking process is calculating the reach and number of page views for all the sites on the Web on a daily basis. The Alexa ranking is obtained by performing the geometric mean of reach and page views, averaged over a predefined period of time (three months).