The foreskin, also called the prepuce, is a flexible section of skin that covers the glans (tip) of the penis and the external opening of the urethra (the tube from which urine and semen exit the body). It can be pulled back to expose the glans and moved back to its original position.
The foreskin protects the glans and keeps the area lubricated. Some experts believe that it also contributes to sexual pleasure because of its sensitive nerve receptors.
Most of the time, the foreskin of newborn boys cannot be retracted. However, most boys can retract the foreskin by the age of three.
Circumcision is a surgical procedure that removes part of or all of the foreskin. It usually done for medical, religious, or cultural reasons.