What is Sexually transmitted disease (STD): also known as sexually transmitted infection (STI) or venereal disease (VD)

A sexually transmitted disease (STD), also known as sexually transmitted infection (STI) or venereal disease (VD), is an illness that has a significant probability of transmission between humans or animals by means of sexual contact, 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 infection (STI) has been preferred, as it has a broader range of meaning; a person may be infected, and may potentially infect others, without showing signs of disease.

Some STIs can also be transmitted via use of an IV drug needle after its use by an infected person, as well as through childbirth or breastfeeding. Sexually transmitted infections have been well known for hundreds of years.