What is an STD?

An STD is a sexually transmitted disease and most people will have an STD in their lifetime. It's estimated that there are 19 million new cases of STDs in the U.S. each year. One of the reasons why STDs are so common is because they are often "silent." You can be infected without showing any sign of an infection. STDs are often passed through sexual activity but can be passed to an unborn child during pregnancy, through IV drug needles, skin-to-skin, or through breastfeeding. 

Sexually transmitted infections (STI), also previously referred to as sexually transmitted diseases (STD) and venereal diseases (VD), are illnesses that has a significant probability of transmission between humans by means of human sexual behavior, including vaginal intercourse, oral sex, and anal sex. While in the past, these illnesses have mostly been referred to as STDs or VD, in recent years the term sexually transmitted infections (STIs) has been preferred, as it has a broader range of meaning; a person may be infected, and may potentially infect others, without having a disease. Some STIs can also be transmitted via the use of IV drug needles after its use by an infected person, as well as through childbirth orbreastfeeding. Sexually transmitted infections have been well known for hundreds of years.