Google Analytics tells you everything you want to know about how your visitors found you and how they interact with your site.

You’ll be able to focus your marketing resources on campaigns and initiatives that deliver ROI, and improve your site to convert more visitors. You can track visitors from all referrers, including search engines, display advertising, pay-per-click networks, email marketing and digital collateral such as links within PDF documents.

Integrated with AdWords, users can review online campaigns by tracking landing page quality and conversions (goals).