The age of majority is the threshold of legal adulthood as recognized or declared in law. It is the moment when minors cease to be considered such and assume legal control over their persons, actions, and decisions, thus terminating the control and legal responsibilities of their parents or guardian over them. Most countries set the age of majority at 18, but some jurisdictions have a higher age and others lower. The word majority here refers to having greater years and being of full age as opposed to minority, the state of being a minor. The law in a given jurisdiction may not actually use the term "age of majority". The term typically refers to a collection of laws bestowing the status of adulthood. Those under the age of majority are referred to as minors and may be legally denied certain privileges or rights (e.g. the right to vote, buy alcohol, marry, sign a binding contract).

Age of majority should not be confused with the age of maturity, age of sexual consent, marriageable age, school-leaving age, drinking age, driving age, voting age, smoking age, gambling age, etc., which each may be independent of and set at a different age from the age of majority.