Foreskin

The Sex Organs - The Male Sex Organs

The External Sex Organs: The Penis

Foreskin
Toward the end of the penis some of this skin forms a freely hanging fold known as the foreskin or prepuce. This foreskin normally covers the tip or head of the penis called the glans. In the case of an erection, however, the glans protrudes from the foreskin and becomes fully exposed.