a World Population Clock?!?

I have a friend who has this rare and remarkable knack for discovering odd online sources for truly strange and kinda mind-boggling information. For instance, the "world POP clock" provided by the U.S. Census Bureau. The clock provides monthly world population estimates - ? The U.S. Census Bureau website also offers world rates of deaths and births and an estimate of the 'natural increase' for the current expressed year, month, day, hour, by minute, per second - ??? How they do this and how my friend simply happens upon this kind of stuff, I dunno.