Does Sunday come at the beginning or the end of the week?

In Europe, business often keep records by week number. The international standard ISO 8601 defines the numbering system for weeks with each week beginning on Monday. In European countries, calendars are almost always arranged with Monday in the first column.

However, in the traditional Islamic and Hebrew calendars, Sunday is literally the "first day" of the week.

In Israel, the working week begins on Sunday and ends on Thursday or Friday at noon, to accommodate the Jewish Sabbath, which begins Friday night. In Islam, Friday is a Muslim holy day when Jummah prayers take place. Consequently, in many (but not all) Muslim countries, the working week is either Saturday through Wednesday or Sunday through Thursday (an increasing number of Muslim countries are adopting the latter). In most other countries in the world, the working week is Monday through Friday.