Sexually transmitted diseases (STDs)-also referred to as sexually transmitted infections (STIs)-are those spread by sexual contact. They may also be spread from a pregnant woman to her fetus before or during delivery.
Exposure to an STD can occur anytime a person has sex or close contact that involves the genitals, the mouth, or the rectum with another person, but exposure is more likely if a person has many sex partners or does not use condoms. STDs can be prevented by not having sexual contact (abstinence).
STDs include:
Most STDs can be treated and cured, but some cannot. Some STDs, such as HIV and syphilis, can cause death.
WebMD Medical Reference from Healthwise