The 12 months beginning Jan. 1 and ending Dec. 31 constitute a calendar year. It is the most commonly used type of accounting year by both individuals and businesses.

For centuries, humans struggled to sync civil, religious, and agricultural calendars with the solar year. Adding a ‘leap year’ solved the problem—though just for the next 3,300 years.

The calendar year, as the name implies, follows the structure of a standard calendar and begins on January 1. A fiscal year lasts for the same duration -- 365 days -- but can begin any time as ...

Muharram. 26 June-27 June 2025 Muharram marks the first month of the Islamic calendar, with the beginning of the year being celebrated on the 10th day of the month (Day of Ashura).

At that point, Earth will rotate a little more slowly, and a calendar year will correspond to precisely 365.0000 days. Beyond that point, we’ll need to start having “reverse” leap years, ...