There exist many different and overlapping definitions of "youth":
- youth is defined as those aged 14-25, both in school and out of school -- and this is generally the approach taken in this book.
- The UN formally defines youth as 15-24.
- Under the UN Convention on the Rights of the Child, there is a clear distinction between those under 18 (children) and those over 18 (adults).
- Many African and Asian youth organizations allow their members to be aged up to 35.
- some consider only students in high school part of their "youth programme", while others include 35-year-old post-graduate students within their youth programmes, as long as they participate through student groups.