...sucking up our time and pumping out ad revenue. Nearly a billion people around the world now look at Facebook daily. The company runs the second-most-popular website in the world and the most-used mobile app in the United States. American users spend nearly as much time on the site per day (39 minutes) as they do socializing with people face-to-face (43 minutes). That has turned Facebook into an online advertising behemoth that generated $12.5 billion in revenue in 2014.