Manhood is the period in a male's life when he has left behind the innocence of childhood. It is during this period that the peak of a man's lifetime is reached. Throughout history, especially in the ancient cultures, boys would undergo many different, sometimes dangerous, ceremonies or sacrifices in order to be recognized as adult in their own right. This rite of passage from childhood to adulthood was very important to these emerging members of society, and many factors of their adult life would sometimes have been affected by this one transitional period of a male person's life.
Manhood is also a euphemism for penis, as well as a synonym for masculinity.