If Sunday's the start of the week, why is it called a weekEND?

Well, here Sunday is the start of the weekend because everything here starts on Sunday..school or work or whatever.. and not Monday.. idk about you guys.. but calling Sunday the start of the weekend does make sense to me.

Sunday and Saturday are on the ends of the weekdays.

Cause it is ending the five days of school and work that some people have to attend so a weekend is the week where you can relax from the stretch of weekdays and do other things you love.