- Sexually transmitted diseases (STD), also referred to as sexually transmitted infections (STI) and venereal diseases (VD), are illnesses that have a significant probability of transmission between humans by means of human sexual behaviour.
- 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.
- Sexually transmitted infections have been well known for hundreds of years, and venereology is the branch of medicine that studies these diseases.
