Quantcast is a major international website ranking service, among other things, and ranks the websites based on monthly visitors to them. Quantcast directly measures the traffic, instead of relying on indirect methods. Therefore, it is often considered to be the most accurate ranking system. You can register your website with Quantcast for tracking your traffic and to get a variety of analytics data and reports. Its audience reports are highly insightful and can be leveraged to make phenomenal improvements to your SEO strategy. You can check your Quantcast Rank in this section simply by typing your website domain here and clicking on the Analyze button.