Final answer:
Societies base their calendars on astronomical events such as the Earth's rotation and the Moon's cycles. The Gregorian calendar is widely adopted and uses leap years to align with the solar year. Some cultures maintain lunar calendars alongside the solar calendar.
Step-by-step explanation:
All societies base their calendars and timekeeping systems on astronomical events such as the rotation of Earth, and the cycles of the Moon and Sun. The basic unit of time, the day, is traditionally based on the solar day, which is the time it takes for the Sun to return to the same position in the sky. Mean solar time averages this value over the year. The calendar is also an important part of timekeeping, being a system to organize days for social, religious, commercial, or administrative purposes.
Early societies and cultures, from Babylonians to the Maya, created calendars to govern agricultural practices and religious observances, basing them on careful observations of the astronomical bodies. Most modern societies have adopted the Gregorian calendar, which was established in 1582 to correct for discrepancies in the Julian calendar. This calendar uses leap years to align the calendar year with the solar year.
Despite the universal adoption of the Gregorian calendar, various cultures still maintain lunar calendars, where the months are based on the cycle of the Moon's phases. These calendars are typically used alongside the solar calendar, sometimes resulting in a hybrid approach to timekeeping.