Allowing the selection of the first day of the week
Countries and regions around the world have different weekends and consequently begin the week on different days.
In North America and in Europe, Monday is the first day of the week. However, on North American calendars, Sunday is the first day of the week; in many European calendars, Monday is the first day of the week. In Saudi Arabia, the weekend is on Thursday and Friday, and Saturday is the first day of the week. In Egypt, the weekend is on Friday and Saturday, and the week starts on Sunday.