Nearly every four years, the Gregorian calendar — which is used in the majority of countries around the world — gets an extra day: February 29. For some people, leap day means frog jokes and ...

NEW YORK (AP) — Leap year. It's a delight for the calendar and math nerds among us. So how did it all begin and why? Have a look at some of the numbers, history and lore behind the (not quite) every ...