Adult
Biologically, an adult is a human or other organism that has reached sexual maturity. In human context, the term adult additionally has meanings associated with social and legal concepts. In contrast to a "minor", a legal adult is a person who has attained the age of majority and is therefore regarded as independent, self-sufficient, and responsible. The typical age of attaining adulthood is 18, although definition may vary by legal rights and country.
Community
A community is a small or large social unit (a group of living things) who have something in common, such as norms, religion, values, or identity. Communities often share a sense of place that is situated in a given geographical area (e.g. a country, village, town, or neighborhood) or in virtual space through communication platforms. Durable relations that extend beyond immediate genealogical ties also define a sense of community. People tend to define those social ties as important to their identity, practice, and roles in social institutions like family, home, work, government, society, or humanity, at large. Although communities are usually small relative to personal social ties (micro-level), "community" may also refer to large group affiliations (or macro-level), such as national communities, international communities, and virtual communities.
Youth
Youth is the time of life when one is young, and often means the time between childhood and adulthood (maturity). It is also defined as "the appearance, freshness, vigor, spirit, etc., characteristic of one who is young". Its definitions of a specific age range varies, as youth is not defined chronologically as a stage that can be tied to specific age ranges; nor can its end point be linked to specific activities, such as taking unpaid work or having sexual relations without consent.