The penis is an organ found in males that has a dual purpose of sex and urination. It is composed of three columns of tissue that is erectile in nature. The penis enlarges to reach an erect state during sexual activity purely due the supply of excess blood to its tissues.

The two tissues that form the erectile part of the penis are the "corpus cavernosum" and the "corpus spongiosum". Two columns of the former lie adjacent to each other on the upper side of the penis, while the latter lies on the underside. The glans penis is formed of the enlarged and cone-shaped part of the corpus spongiosum. This part also supports the foreskin( prepuce), a piece of loose skin that normally protects the glans penis, but can retract in adults to expose the glans penis for greater sensitivity during sex. The place where this foreskin is attached, on the base of the glans penis, is called frenum.

The urethra is the passage for both urine and semen through the corpus spongiosum, and comprises the last part of the urinary tract. Its tip is called the "meatus" and is the opening at the tip of the penis. The all-important sperms are produced in the testes below the penis and are stored in the epididymis attached to them.

The last part of the male penis is the raphe. This prominent ridge runs along the base of the penis between the lateral halves of the penis. It originates at the meatus, runs along the entire length of the penis, then across the scrotum to the area between the scrotum and the anus, called the perineum.