Alexa, founded in 1996, and showing all the measurement tool to analyze websites in the world according to various criteria in the ranking of countries where it serves around the world and websites. For example, you type a site in Turkey will show you the ranking of the world and Turkey.
Due to this area it is quite old in a very large database, since the database has to look at their first measurement tool to learn about a website by internet users.
Alexa, when analyzing a website, whether from search engines that visitors come to the site directly, how many pages they visit the site and consider how much time they spend.
Alex, along with the not 100% accurate data is deemed reliable data given approximately and allows us to have an idea about the approximate site.www.alexa.com