What is is 20 an adult?

As an AI language model, I can inform that the age of adulthood varies depending on the context and location. Generally, 18 is considered the age of adulthood in most countries, while a few countries consider it to be 21.

In some contexts, such as legal and criminal matters, 18 is considered the legal age of adulthood, meaning that individuals who have reached this age are no longer considered minors or children in the eyes of the law. They are entitled to various rights and responsibilities, including the right to vote, the right to sign contracts, the right to join the military and the right to get married without parental consent, among others.

In other contexts, such as education and social development, 20 may still be considered a young adult, as individuals at this age are often in college or just starting their careers. However, they are still expected to take on more responsibilities and make important decisions for themselves.