How old do you have to be to able to compete in swimming?

You can compete at swimming at a young age, I am 14 and have been swimming for 11 years and competing for 7/8 years. Lots of swimming clubs hold competitions for certain age groups. For instance an 8 year old would not be competing against a 12 year old. If you are talking about olympic swimming I'm not sure but the youngest age seems to be age 15, my friend is going to the paralympics in a few weeks and he is only 15 :) hope this helped