According to US Legal, the age of majority is 18. The age in which one is defined as an adult is the age that one is granted full adult rights such as the right to vote, get married and enlist.
According to the MIT Center for Work, Family and Personal Life, one is considered a young adult between the ages of 18 and 25. Individuals that are over the age of 25 are considered to be in later adulthood. According to US Marriage Laws, minors who are legally emancipated gain certain rights that are usually restricted until the age of 18. For example, a legally emancipated minor can choose where to live without the consent of an adult.