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 (U.S. English), is the part of the seven-day week devoted to labour. In most Western countries it is Monday to Friday. Weekend is a time period including Saturday and Sunday. Some people extend the weekend to Friday nights as well. In Christian tradition, Sunday is the "Lord's Day" and the day of rest and worship. Jewish Shabbat or Biblical Sabbath lasts from sunset on Friday to the fall of full darkness on Saturday, leading to a Friday-Saturday weekend in Israel. Islam declares Friday as a day of rest, so Muslim-majority countries usually have a Thursday-Friday or Friday-Saturday weekend. The French Revolutionary Calendar had ten-day weeks and allowed decadi, one out of the ten days, as a leisure day.

The present-day concept of the weekend first arose from the Dies Solis (Day of the Sun) decreed by Constantine and from Biblical Sabbath.[citation needed] The Christian Sabbath itself was just one day each week, but the preceding day (the Jewish Sabbath) also came to be taken as a holiday 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. Proposals have continued to be put forward for further reductions in the number of days or hours worked per week, on the basis of predicted social and economic benefits.