2016 is a leap year and 29th February (today!) was your extra day.
I am sure you have lots of questions on how a leap year comes about and so here is astrophysicist and all-round science dude Neil deGrasse Tyson to explain all about the 365 and a quarter days (or so) that it takes us to orbit the sun.
I had absolutely no idea about the 100 Year Rule and the 400 Year Rule to incrementally manage this extra day. Fascinating.
Hope you didn’t waste your leap day!