Leap year, what is it and why do we have it? It comes every 4 years, and what changes is they add the 29th day to February. We have leap year to keep our clocks up with the Earth’s gravitational clock. It is also said that leap day is the day women propose to men. This started for a nun in Ireland. To say that leap year is just for our Earth’s rotation, it has a change in time by one day. Instead of 365 days, there is 366. Some people think that it has no reason but I think it’s just science and we just have to go with nature. There is no real nature.