How many cups of water should everyone have per day?!

How many cups of water should everyone have per day?

i dont know what to believe some people tell me that you should have 4 and others say 8 i want to know exactly how much of water should i have?

tthe whole thing about 8 cups a day is not necessarily true. i learned at school that it was a way for water bottle companies to make money, to tell everyone they had to drink sooo much. u just need to drink so that ur not thirsty, and alittle more. and if u excercize then of course drink alot. u will know if u did not have enough to drink each day, if u get super thirsty at night before bed(water will taste really good).