Year

A year is a period of time used to organize a complete cycle of Earth's movement around the Sun. Earth takes about 365.24 days to complete one orbit, which is why a calendar year normally has 365 days. Because the extra fraction of a day adds up over time, most calendar systems that follow the Gregorian calendar add one day to February every four years, creating a leap year of 366 days.

This adjustment keeps the calendar broadly aligned with Earth's position in its orbit. A year is divided into twelve months, although the months do not all have the same number of days. The length of a year is also related to the changing seasons, but the seasons are caused mainly by Earth's axial tilt as it travels around the Sun, not simply by its distance from the Sun.

Years help us measure long periods and organize events in our lives. We use them to record birthdays, plan school years, compare historical dates, and describe the ages of people, animals, buildings, and other things. In many places, the year is also divided into four seasons, although the timing and characteristics of those seasons vary according to location.

Different cultures have developed different calendars, and their ways of numbering or beginning a year may differ. The Gregorian calendar is widely used for civil purposes, but other calendars remain important for cultural, religious, or traditional reasons. As Earth continues its orbit, one year follows another, providing a useful way to understand the passage of time.