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 time and to plan events. They can be used for a variety of purposes, such as scheduling appointments, tracking deadlines, and planning vacations.
The Gregorian calendar is the most widely used calendar in the world today. It was introduced by Pope Gregory XIII in 1582 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 most years and 29 days in February in leap years. Leap years occur every four years, except for years that are divisible by 100 but not by 400.
