Google Analytics is a service offered by Google that generates detailed statistics about a website’s traffic and traffic sources and measures conversions and sales. It’s the most widely used website statistics service. The basic service is free of charge and a premium version is available for a fee. Google Analytics can track visitors from all referrers, including search engines and social networks, direct visits and referring sites. It also tracks display advertising, pay-per-click networks, email marketing, and digital collateral such as links within PDF documents.