Despite how old they may 'look' teens are the age span from thirteen to nineteen. Turning twenty frees you from being a 'teen'. Besides all of that, the Avon Lady thought I was sixteen when I was only thirteen at the time. The ironic twist is when the very same woman saw me three years later and thought I was only thirteen, when she suggested to my mother it may be a few more years before I was ready for her product. LOL Mom and I laughed. I was sixteen. I only grew one-half of an inch in high school. I'm still on the 'short' side.
In my game:
Babies: 0-12 months
Toddlers: 12 months to 4 years (the very act of learning how to walk makes them called toddlers. Some older than two aren't all that sure-footed, either, so they're classified as Toddlers through age 4. and some learn how to walk later than others.)
Children: Hahaha, 5 to 12 years (yes, they are very tall for their ages, or very short for Middle Schoolers)
Teens: 13-17 (with a codicil. Here in the USA kids become officially 'adults' at age18 able to sign contracts, marry, etc.)
YAs: 18-35
Adults: 36-55
Elders: 65- till death us do part
Coming to you with tongue-in-cheek, whilst sitting in my not-so-comfy desk chair.