Check whether any year is a leap year, with the rule explained — plus the next leap years.
A year is a leap year if it is divisible by 4 — except century years, which must also be divisible by 400. So 2000 was a leap year but 1900 was not.
Earth takes about 365.2422 days to orbit the Sun. Adding a 29th of February every four years keeps the calendar aligned with the seasons.
No. 2100 is divisible by 100 but not by 400, so it skips the leap day — a common surprise.