"Under-18" refers to individuals who are younger than 18 years old. This age group is often considered minors and is subject to specific laws and regulations that differ from those for adults. For example, in many countries, individuals under 18 cannot vote, sign contracts, or drink alcohol. In various contexts, such as education and sports, "under-18" categories are used to create age-appropriate opportunities. For instance, youth sports leagues often have under-18 divisions to ensure fair competition among players of similar ages. Additionally, many educational programs are designed specifically for this age group to support their development.