At what age does a person become a teenager?

Well considering the persons maturity. You are a pre-teen from 10-12 since you are just figuring things out and seriously annoying. A tween from 13-14 since you are way too confident and still really annoying. I wouldn't say someone is considered a teenager until they are 15 but like i said it all depends on maturity. If you still act like a child you are not a teen. A teen is almost an adult You aren't a teenager until 15-16 and that ends around 19.