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 or workday is any day of the working week. Other institutions often follow the pattern, 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 Christian Sabbath was just one day each week, but the preceding day (the Jewish Sabbath) came to be taken as a holiday as well in the twentieth century. This shift has been accompanied by a reduction in the total number of hours worked per week, following changes in employer expectations. 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 Amalgamated Clothing Workers of America Union was the first to successfully demand a five-day work week in 1929.