HubSpot tracks great information on every visitor to your website, including how many times he visited, where he came from the first time he visited (i.e. Google keyword search, a specific blog link, advertisement, etc.), whether he subscribed to your blog, which articles he commented on, which web pages he visited, etc. When a prospect "self-selects" by filling out a form on your website, his contact details along with all of the "intelligence" are captured in the HubSpot lead tracker and you are notified to follow up with him.
This lead intelligence allows you to have a more intelligent first conversation with this prospect because you already know what he's interested in and this gives you the power to turn prospects into customers at a much higher rate. In addition, you will be able to observe trends on what marketing programs, search terms, blog links, etc. are driving the most qualified prospects into your funnel.
Track your leads' path through your site and capture intelligence about them that helps you qualify your leads and close more sales