Alexa Traffic Rank is based on three months of historical traffic data from Alexa Toolbar users and data obtained from other, diverse traffic data sources, and is a combined measure of page views and users (reach). Alexa computes the reach and number of page views for all blogs on the Web on a daily basis. The main Alexa traffic rank is based on a value derived from these two quantities averaged over time (so that the rank of a blog reflects both the number of users who visit that blog as well as the number of pages on the blog viewed by those users). The three-month change is determined by comparing the blog's current rank with its rank from three months ago. The three-month change would show the difference between the rank based on traffic during the first quarter of the year and the rank based on traffic during the second quarter.