A teen is a person between the ages of thirteen and nineteen. The word comes from the “teen” ending of these numbers: thirteen, fourteen, fifteen, sixteen, seventeen, eighteen, and nineteen. Once you turn twenty, you're no longer a teen.

Being a teen means you're not quite a child anymore but not yet an adult either. Teens experience major physical changes as their bodies grow and develop. They also face new responsibilities and freedoms, like staying home alone, getting a driver's license, or holding a first job. Friendships often become more intense during these years, and teens start thinking more independently about their beliefs and values.

Today, the teen years are recognized as a distinct phase of life with its own challenges and opportunities.

Parents and teens sometimes clash because teens want more independence while parents worry about keeping them safe. Teachers know that teens can achieve remarkable things when given challenging work, though they also need more sleep than younger kids (even if they stay up late anyway). Scientists have discovered that teen brains are still developing, especially the parts that handle planning and decision-making. This helps explain why teens sometimes take risks that adults wouldn't.