About Sundays

Sunday is the day of the week between Saturday and Monday. It is considered a non-working day in many countries of the world, and is part of "the weekend". Countries predominantly influenced by Jewish or Islamic religions have Friday or Saturday as a weekly non-working day instead.

The Gregorian calendar repeats every 400 years, and no century starts on a Sunday. The Jewish New Year never falls on a Sunday. Any month beginning on a Sunday will contain a Friday the 13th.

- Text from Wikipedia.org