A calendar is a system of organizing days for social, religious, commercial, or administrative purposes. The word “calendar” comes from the Latin word “calends,” which referred to the first day of the month in the Roman calendar. Calendars are used to keep track of appointments, events, and holidays. Businesses use calendars to schedule meetings, track deadlines, and plan projects. Schools use calendars to plan the academic year and schedule classes and exams. Families use calendars to keep track of appointments, activities, and vacations.
The Gregorian calendar is the most widely used calendar in the world today. It was introduced in 1582 by Pope Gregory XIII and is based on the solar year, which is the time it takes for the Earth to orbit the sun. The Gregorian calendar has 12 months, with 28 days in February in a common year and 29 days in February in a leap year. Leap years occur every four years, except for years that are divisible by 100 but not by 400.
