Google Analytics
Google Analytics is a type of service provided by Google, that offers statistics regarding the traffic of a particular website as well as the traffic sources. It also measures all the conversions and sales on the website. Google Analytics is mainly developed for marketers, not webmasters. GA tracks visitors from search engines and social networks. It also provides detailed information on the advertisements, pay-per-click networks, email marketing and many more. The basic program is free and available to everyone, however, the premium version can be downloaded for a certain fee.
Google Analytics provides you the best measurement tools for your business.