ELI5: Explain Like I'm 5

Year

A year is a measurement of time - it's 365 days long. Each day is 24 hours, 60 minutes and 60 seconds long. In a year, we have 12 months (January, February, March, April, May, June, July, August, September, October, November, December). Each month has an average of 30 or 31 days, except for February, which has 28 days in most years. There are also special years called leap years, which have 29 days in February. The reason for this is so that the calendar stays in sync with the movement of the Earth around the Sun, which takes 365 and a quarter days.