Technically, Monday is the first day of a week. Saturday and Sunday are called the weekend for a reason. However, some calendars often throw us off, because the calendar starts each week with a Sunday. There are many calendars that display Monday as the first day of the week.
Also, in Christianity, God took a rest from creating the Earth on the seventh day, which we call Sunday and is the main day that most Christians go to church to worship.
Yes, if your week starts with Sunday.
Sunday is usually the first day of the week on North American calendars.
Sunday is the first day of the week in British countries.
It doesn't have a fixed day of the week. Rather, it has a fixed day of the month: it starts on the 25th of Kislev.
It was a Saturday.
The first day in April was a Friday.
August starts on a different day of the week every year, but in August 2012 it started on a Wednesday. Otherwise it starts on the first every year!
July starts on a different day of the week every year. In 2012, it started on a Sunday.
The French week starts on Monday (lundi) and ends on Sunday (dimanche).
2011 starts on a Saturday.
Tommorow
Summer officially starts in the fourth week of June, specifically on June 21st or 22nd. This day is known as the summer solstice, marking the longest day of the year in the Northern Hemisphere.