At first glance, a visit seems pretty straightforward: it begins when a visitor comes to a website and ends when they leave. But try to measure a visit and things get a little tricky. For example, if a visitor reads an article on your site, follows a related link to another site, then returns to your site afterward, should that count as one visit or two? Or suppose someone comes to your web page and then starts working on something else, leaving their browser open in the background. If they click back to your site eight hours later, should that be considered a separate visit, or just one mighty long stay? According to the Media Measurement Task Force at the Internet Advertising Bureau (IAB), a visit is “a series of page requests by a visitor without 30 minutes of inactivity” – which just goes to show how arbitrary the measurement of a visit can be.