The prostate is a small gland in the male body, about the size of a walnut. It sits below the bladder and surrounds part of the tube that carries urine out of the body. The prostate helps make fluid for semen, which helps protect and nourish sperm. During ejaculation, it helps push this fluid into the urethra. Because of where it sits, a larger prostate can make it harder for urine to flow. The prostate usually gets bigger with age, and prostate cancer starts in this gland.
Infographic showing the prostate gland, its location, and its main functions.