An adult is a person who has attained the age of majority. The age of majority is the legally defined age at which a person is considered an adult, with all the attendant rights and responsibilities of adulthood. The age of majority is defined by state laws, which vary by state, but is 18 in most states. Rights acquired upon reaching the age of majority include the rights to vote and consent to marriage, among others. However, the right to vote is 18 nationwide under the 26th Amendment to the Constitution, regardless of the state laws.
It is the age at which one becomes a legal adult and gains full legal rights. It is also the age at which a person is liable for their own actions, such as contractual obligations or liability for negligence. In general, a parental duty of support to a child ceases when the child reaches the age of majority.
The age of majority may be relevant in matters, among others, such as guardianships, defining the head of households, legal standing to bring lawsuits, foster care, alcohol purchases, emancipation, licensing, and marriage.
For example, in banking and investment accounts, the financial institution may provide that in any account established by a minor, the institution reserves the right to require the minor account to be a multiple party account with an owner who has reached the age of majority under state law, who shall be jointly and severally liable the institution for any returned item, overdraft, or unpaid charges or amounts on such account. Rules vary by institution.