The prostate is a small gland below the bladder and near the rectum in men. It surrounds the urethra, the passage to the penis through which urine and semen pass.

The prostate gland is part of the reproductive system. It produces most of the fluid that makes up semen, which enriches and protects sperm. To grow and develop, the prostate relies on the male hormone testosterone, which is made by the testicles.

The prostate is often described as being the size of a walnut and it is normal for it to grow as men age. Sometimes this can cause problems, such as difficulty with urinating.