The term "leap year" probably comes from the fact that a fixed date in the Gregorian calendar normally advances one day of the week from one year to the next, but the day of the week in the 12 months following the leap day (from March 1 through February 28 of the following year) will advance two days due to the extra day, thus leaping over one day in the week. For example, Christmas Day (December 25) falls on a Friday in 2020, Saturday in 2021, Sunday in 2022 and Monday in 2023, but then will leap over Tuesday to fall on a Wednesday in 2024.