At what age are you an adult?

Answer 1

This is dependant apon the country in which you live - but generally around 18. Some countries it is 16 but in other 21. Not sure of what area you are referring to. Here is a link to age of consent for all states: http://www.ageofconsent.com/ageofconsent.htm

Answer 2

18.

although some activities do have different minimum ages - for example, you cannot drink or gamble until 21, and cannot rent a car until 23.
18, most places.

Depends what your asking for though, you can be charged as an adult at 17.