Herpes is a name given to a common viral infection. The infection can occur in the mouth and in the genitals.

The two forms of herpes are caused by two forms of a herpes virus. Both forms are called herpes simplex virus. Oral herpes is generally caused by herpes simplex type 1 (that is typically shortened to HSV-1). It is also known as human herpes virus 1 (HHV1). Genital herpes is generally caused by herpes simplex type 2 (shortened to HSV-2, which has also been called human herpes virus 2, or HHV2). However, HSV-1 can cause genital herpes and HSV-2 can cause oral herpes.

There are eight herpes virus types known in humans. HSV-1 (HHV1) and HSV-2 (HHV2) are the forms associated with oral and genital herpes. Human herpes virus 3 is also known as varicella zoster virus, and is the cause of chickenpox. HHV4 is the...