Work week

The workweek and weekend are those complementary parts of the week devoted to labour and rest, respectively. The legal working week (British English), or workweek (American English), is the part of the seven-day week devoted to labour. In most of the Western world, it is Monday to Friday; the weekend is Saturday and Sunday. A weekday is any day of the working week. Other institutions often follow the same days, such as places of education.

In some Christian traditions, Sunday is the "day of rest and worship". Jewish Shabbat or Biblical Sabbath lasts from sunset on Friday to the fall of full darkness on Saturday; as a result, the weekend in Israel is observed on Friday–Saturday. Some Muslim-majority countries historically had a Thursday–Friday or Friday–Saturday weekend; however, recently many such countries have shifted from Thursday–Friday to Friday–Saturday, or to Saturday–Sunday. The French Revolutionary Calendar had ten-day weeks (called décades) and allowed décadi, one out of the ten days, as a leisure day.

The present-day concept of the 'week-end' first arose in the industrial north of Britain in the early part of nineteenth century and was originally a voluntary arrangement between factory owners and workers allowing Saturday afternoon off from 2pm in agreement that staff would be available for work sober and refreshed on Monday morning. The term weekend is first recorded and defined in the British magazine Notes and Queries in 1879:

...
Wikipedia