Organisms can either be grouped as male or female. Female humans are called women and their bodies are different from male humans (who are called men). A woman has a vagina between her legs (a male has a penis) which is the main sexual organ. They also have breasts with milk glands, which allow them to nurse (feed) infants. A woman's shoulders are usually not as wide as a man's, but women usually have wider hips than men, because they need wide hips to be able to give birth.