<Tr> <Td> </Td> <Td> This article needs additional citations for verification . Please help improve this article by adding citations to reliable sources . Unsourced material may be challenged and removed . (September 2013) (Learn how and when to remove this template message) </Td> </Tr> <P> Sunday is the day of the week between Saturday and Monday . Sunday is a day of rest in most Western countries, as a part of the weekend and weeknight . </P> <P> For most observant Christians, Sunday is observed as a day of worship and rest, holding it as the Lord's Day and the day of Christ's resurrection . In some Muslim countries and Israel, Sunday is the first work day of the week . According to the Hebrew calendar and traditional Christian calendars, Sunday is the first day of the week . But according to the International Organization for Standardization ISO 8601, Sunday is the seventh day of the week . </P> <P> The name "Sunday", the day of the Sun, is derived from Hellenistic astrology, where the seven planets, known in English as Saturn, Jupiter, Mars, the Sun, Venus, Mercury and the Moon, each had an hour of the day assigned to them, and the planet which was regent during the first hour of any day of the week gave its name to that day . During the 1st and 2nd century, the week of seven days was introduced into Rome from Egypt, and the Roman names of the planets were given to each successive day . </P>

When does a week start sunday or monday