NEW YORK – More than a billion people now log into Facebook each month to check up on old friends, tag photos of new ones and post about politics, religion, cats or what their kids are doing.

That's double the 500 million it hit in July 2010 — what now seems like a lifetime but was a little more than two years ago. August 2008 marked another milestone, 100 million.

The latest milestone also amounts to nearly half of the world's roughly 2.5 billion Internet users, as measured by the International Telecommunications Union.