ELI5: Explain Like I'm 5

Hebrew calendar

The Hebrew calendar is a special calendar used by Jewish people. It is different from the calendar most people use because it follows a lunar cycle rather than a solar cycle. This means that the Hebrew calendar has 12 months, but they are all different lengths, which means that the year is shorter than in the calendar most people use. It also means that Hebrew months start on different days each year. Each year has either 12 or 13 months. In the 12-month years, the months have 29 or 30 days, and in the 13-month years, the months have 29 days. The Hebrew New Year happens in the fall, but the exact date changes each year.