Were you born on February 29? If so, you are one of only about 5 million people in the whole world. Why do we have this extra day every 4 years? While most years contain 365 days, it actually takes the Earth a little bit longer to make its orbit—roughly 365.2421 days, so approximately every 4 years, we tag on one extra day to make up the time. History.com provides 5 things you may not know about Leap Day. And to help you celebrate in style, here are 13 Leap Year traditions from BuzzFeed. No matter what traditions you follow or how you celebrate—Happy Birthday Leaplings!