Navel formation, also known as umbilical cord formation, is the process of forming a navel or belly button. An innie is a navel that is indented and an outie is a navel that protrudes outward. Innies are the most common type of navel formation and are formed when the umbilical cord is cut close to the baby's abdomen. Outies are less common and are formed when the umbilical cord is cut further away from the baby's abdomen.