I don't know if I ever want to get married. Thats a lot of committment.
It really is.  Promising to spend your whole life committed to someone else is a very big moment
The definition of marriage around the world has different meanings and values.
Yes it does.  In a lot of cultures, a married woman is actually considered property of the husband.
For a lot of people you have to wait until marriage to have any sexual activity!
Yes, and that might be why so many people married young in the past.  The average age for people to get married in the 1970s was 21 years old.  Now it is between 26 and 28 years old.
Some cultures participate in arranged marriage, child marriage, polygamy, and sometimes forced marriage.