Quantcast is a media measurement, web analytics service that allows users to view audience statistics for millions of websites. Quantcast Corporation's prime focus is to analyze the Internet's web sites in order to obtain accurate usage statistics by surfers from the USA. Like Alexa, Quantcast rates Web pages by ranks. Quantcast statistics always refer to the usage from the United States, therefore Alexa data and Quantcast data do not always show the same results. Quantcast does not require a toolbar to be installed upon one's web browser to obtain statistics. Instead participating websites voluntarily insert Quantcast HTML code inside Web pages they wish to have included in statistics. This code allows Quantcast to keep track of the traffic directed towards those Web sites.

This SonicWALL signature identifies legitimate Quantcast traffic.