Ans: A Leap year that is commonly known as Bissextile and the intercalary year is the calendar year that contains one additional day. One extra day is added to keep the year synchronized with the seasonal and astronomical year. There is the leap day every four years because our earth completes one rotation around our sun in 365 days and 6-hours. Over the 4 years, these extra 6-hours from each year add up to get entire day i.e. 6*4=24-hours. The month of February is a little bit different from the other eleven months in the sense that in every 4-years, 29th day is added to get and give one whole day. What will be the next Leap year? The next leap year will come in 2020. The last year was in 2016 so the next year will come in the year 2020 (2016+4=2020) Rules of leap years: For the year that may qualify for the leap year satisfied the following conditions: The year should be perfectly divisible by four. e.g. (2012, 2016 and 2020, etc.) If any year is divisible perfectly by the 100, will not be a leap year. If the same year can be divided by 400, then the year will be called leap year like the 1800 year was not the leap year because it is divisible by 100 but not with 400 e.g. years. 1600, and 2000 was a leap year. We hope you will get a better idea about the question why is there an extra day in a leap year.