This is Leap Year

February 29 is a date that occurs only every four years, in years evenly divisible by 4, such as 1988, 1996, 2008 or 2016 (with the exception of century years not divisible by 400, such as 1900) for the Gregorian calendar, which is most widely used in the world today. These are called leap years, and February 29 is the 60th day of the Gregorian calendar in such a year, with 306 days remaining until the end of that year. February 29 is also known as bissextile day or Leap Day.

Read more here:
http://en.wikipedia.org/wiki/Leap_Day