What is Facebook, besides the world’s largest and most popular social networking Web site?

The answer is: an enormous furnace for burning the world’s spare time (and possibly its alleged productive time, too). This is according to a new study by Internet research group comScore. Today, the average Internet user in the U.S. spends more time on Facebook than on Google (which came in second) or Yahoo (which ranked third).

The study also indicated that the amount of time people spend on Facebook continues to rise: just a year ago, data from Nielsen indicated that the average Internet user spent a healthy four hours and 39 minutes on Facebook every month. Today, that figure stands at more than seven hours per week. On average, Internet users spend about 9.9 percent of their time online on Facebook; Google, in second place, burned about 9.6 percent of Internet users’ time online.

The figures for Google include the company’s search engine, its news sites, YouTube (which is owned by Google) and Gmail. Yahoo, coming in third, claimed about 9.1 percent of Internet users’ time.

As of July of this year, Facebook had more than half a billion users worldwide. Though it is predicted that Facebook’s growth will begin to slow in North America, where it has largely saturated the market, aggressive growth is expected to continue abroad in countries such as India, South Korea, Japan and Russia. ComScore’s research has shown that Facebook's membership in India has grown 179 percent, to 20.9 million users, in the past year alone.

It would appear that we are about to share our addiction with the rest of the world. No word on whether they will thank us for it.