Leap years are years which contain 366 days, compared with common years which have 365 days.
The extra day in a leap year is February 29.
Years divisible by 4 are normally leap years, with some exceptions.
All of the years divisible by 4, between 1904 and 2096 inclusive, were or will be leap years.
1900 was not a leap year.
2100, 2200 and 2300 will not be leap years.
The rules for determining leap years are:
- If the year is divisible by 4, it will normally be a leap year. For example, 2016, 2020 and 2024.
- If it is divisible by 100, it will NOT normally be a leap year. For example, 2100 and 2200.
- Exceptions to the exception are years divisible by 400. Years divisible by 400 ARE leap years. For this reason, 2000 was a leap year, and 2400 will be one too.
The reason for the rules is to approximate the true number of astronomical days in a year, which is 365.24.