A sweet sixteen is a coming-of-age party celebrating one's 16th birthday, mainly celebrated in the United States and Canada. While they are not a legal adult, typically, when they turn 16 is when many people learn to drive, get jobs, and assume other adult responsibilities. For many, the 16th birthday celebrates adulthood and marks the end of childhood. As the name suggests, the celebration takes place on a sixteenth birthday and is celebrated among girls and boys, though it is typically more common with girls. In the past, sweet sixteen parties tended to be formal, whereas they tend to be more informal today.

Source: Wikipedia