"Under-21" refers to individuals who are younger than 21 years old. This age group is often associated with certain legal restrictions, such as the legal drinking age in many countries, including the United States. People under 21 may also face limitations in activities like gambling or purchasing tobacco products. In various contexts, being under 21 can impact opportunities, such as employment or participation in certain events. For example, some venues or clubs may have age restrictions, allowing only those who are 21 and older. This age designation is significant in discussions about youth rights and responsibilities.