Weeks

Weeks are a unit of time equal to seven days and are used to organize schedules, work, and publication cycles. They form the basis of most modern calendars, with years divided into 52 or 53 weeks.

The origins of the seven-day week lie in ancient Near Eastern traditions and were adopted by Jewish, Christian, and Islamic cultures. In many languages the names of the days reflect celestial bodies or deities (for example, Sunday corresponds to the sun, Monday to the moon in English). The concept spread widely through Roman and Christian calendars.

In modern usage the ISO 8601 standard defines weeks as starting on Monday and assigns week 1 as the week with the year's first Thursday. Some regions and traditions begin weeks on Sunday. The week year can differ from the calendar year by up to one week.

The modern workweek commonly lasts five days, with two days off, typically Saturday and Sunday; however, weekend days vary by country and culture. Some places observe Friday–Saturday weekends, and others have different public days.

Throughout history some alternative week systems have been tried, such as ten-day weeks in the French Republican Calendar and five-day weeks in the Soviet Union. Today the seven-day week remains the globally dominant convention.