Measuring conversion events and conversion rates is one of the most popular uses of web measurement tools.
Loosely defined, a conversion rate measures the number of visitors who took the action you wanted on your site divided by the total number of visitors. Every end-goal conversion, like a purchase, is composed of many other conversion points, like the click-through path in a shopping cart. Before you can measure conversion rates and determine how to improve conversion on your site, the ultimate goal, you first need to establish a strategy for defining conversion events.
Most people don't really give the identification of conversion events enough thought. They simply think "Well, if a visitor makes a purchase or generates a lead, that is good enough for us," but while purchase is a very important conversion event, it is by no means the only one worth measuring. You should define conversion events as any activity visitors can engage in that is valuable to your organization. Here are some example conversion events you may want to measure once you recognize that the definition of conversion is broad.
Makes a purchase
Opts into a newsletter
Submits some type of personal information
Subscribes to an RSS feed
Prints a page
Uses "email this page to a friend" functionality
Spends more than 10 minutes browsing the site
Downloads a document or application
Looks at a set of important pages
Views a set number of pages during a visit