The Clitoris.
It is the most sensitive area of the female genitalia. Only the head of the clitoris is directly visible. The only known function of the clitoris is to focus and to accumulate sexual sensation and erotic pleasure. During maximum stimulation, the clitoris retracts. The retracted clitoris continues to receive stimulation through indirect pressure and traction. The key to maximum pleasure is discovering how best to stimulate the clitoris and how much stimulation to apply.