Sexually transmitted diseases (STDs) vary in their susceptibility to treatment, their signs and symptoms, and the consequences if they are left untreated. Some are caused by bacteria. These usually can be treated and cured. Others are caused by viruses and can typically be treated but not cured. As of June 2002, recent advancements in diagnosis now allow the identification of more than 15 million new cases of STD in the United States each year.

Long known as venereal disease, after Venus, the Roman goddess of love, sexually transmitted diseases are increasingly common. The more than 20 known sexually transmitted diseases range from the life-threatening to painful and unsightly. The life-threatening sexually transmitted diseases include syphilis, which has been known for centuries, some forms of hepatitis, and Acquired Immune Deficiency Syndrome (AIDS), which was first identified in 1981.

Most sexually transmitted diseases can be treated successfully, although...