Nipples are small, protruding structures located on the surface of the breasts in both males and females. They serve as the outlet for milk in females during breastfeeding, connecting to the mammary glands. Nipples can vary in size, shape, and color among individuals. In addition to their role in lactation, nipples are also sensitive areas of the body, containing many nerve endings. This sensitivity can contribute to sexual arousal in some people. Nipples are present in all mammals, including humans, and play a role in the reproductive process.