Size
Penis length, measured along the top, averages 3 1/2 to 4 inches when flaccid (soft) and 6 to 6 1/2 inches when erect (hard), but there’s a wide range of normal lengths. Penis size when soft also varies with temperature and emotions. It may appear smaller in an overweight male who has a large fat pad under the pubic hair.

Anatomy
The penis consists of the shaft, the glans (head), and the prepuce (foreskin). The urethra is the tube that passes through the penis and transports both urine from the bladder and semen (ejaculate or “cum”) from the testicles.

Circumcision
This term refers to surgical removal of the foreskin, and it is commonly performed in newborn males for cultural or religious reasons. Later in life, circumcision may be performed to correct phimosis, a condition in which the foreskin remains tight and cannot be pulled back over the head of the penis. It is important for uncircumcised males to fully retract the foreskin each time they urinate, and to clean under the foreskin daily when they shower or bathe. A circumcised penis may be referred to as “cut” while an uncircumcised penis is “uncut.” The presence or absence of the foreskin has no effect on sexual performance. For most American males, circumcision is a matter of parental preference.

Erections
An erection (and there are dozens of slang terms like “hard-on” or “woodie”) occurs when the penis, which contains two cylinders of sponge-like tissue, fills with blood. Although erections have been called “boners,” there are no bones in the penis. When an erection occurs, the foreskin retracts (pulls back) over the head of the penis. Erections commonly occur in response to sexual thoughts and physical stimulation of the penis, during sleep in association with nocturnal emissions (“wet dreams”), and spontaneously for no apparent reason, often unexpected.

Bumps
Common “bumps” on the surface skin of the penis include sebaceous glands, pearly papules and inflamed hair follicles. Sebaceous (oil) glands are yellow raised bumps on the shaft, which may secrete a small amount of waxy material. Pearly penile papules may also develop during puberty and may be mistaken for sexually transmitted genital warts. These tiny raised flesh-colored bumps are found in rows along the rim (corona) of the head of the penis. Both sebaceous glands and pearly papules may persist into adulthood, and require no treatment. Pubic hairs at the base of the penis may become infected with skin bacteria such as Staph, resulting in folliculitis. This produces red bumps and pus in the hair follicles, and may require antibiotic treatment if extensive.