What age does youth mean?

In different societies around the world, the meaning of youth is different, and the definition of youth has been changing with the changes of political, economic, social and cultural environment. Due to different social, cultural, institutional, economic and political factors.

In many countries, the age of majority usually refers to 18 years old. Once a person exceeds this age limit, he is considered an adult. However, due to different social, cultural, institutional, economic and political factors, there are subtle differences in the actual definition and understanding of the word "youth" in different countries.