The term penetration has several meanings, depending on its context. Generally speaking, it refers to the act or process of breaking through a barrier or reaching an objective. In specific terms, penetration can refer to: 1) sexual intercourse; 2) the ability of a product or service to gain acceptance in the marketplace; 3) the success of military forces in breaching enemy defenses during combat; and 4) the depth at which something is able to pierce through an object.