The labia are folds of skin that form the vulva, the external female genitalia. From the Latin for "lips," they consist of three parts: the labia majora, labia minora and the labial commissure. The labia majora are the thick outer lips. The labia minora are thinner and smaller and located just within the labia majora directly around the opening of the vagina. The anterior and posterior labial commissures mark the corners where the two sets of lips meet. The labia as a whole have several important functions within the female body.
The labia majora protects the internal organs of the female reproductive system by preventing the vagina from opening outside of sex. Its thick, tough lips safely enclose the delicate inner membranes and hide the vaginal opening. The original function of the pubic hair that covers the external labia dates from man’s earliest history when bodies were unclothed. The hairs acted as a trap for foreign bodies such as insects. In the same way, the labia minora act as a protective barrier for the urinary tract.
The labia guard the vulva against bacterial attacks. The glands of the inner labia minora produce secretions rich in chemicals designed to kill bacteria. In this way, the labia protects itself from infections.
The glands of the labia minora also facilitate successful intercourse. When the membranes of these inner lips are stimulated by touch or pressure, glands are stimulated to produce secretions. The resulting lubrication helps keep the labia and the vagina moist and aid penetration.
The labia’s function during intercourse is not purely practical; they also help women enjoy sex. The thin membranes of the labia minora are packed full of blood vessels and nerves that swell when stimulated. This makes the inner lips incredibly sensitive and receptive. In the right circumstances and with appropriate stimulation, the labia will produce sensations of pleasure, aiding successful intercourse by increasing female receptiveness.