Herpes simplex virus (HSV) is a viral disease that can cause cold sores or genital herpes. It was first recognized by Hippocrates in ancient Greece. There are two types - HSV-1 typically causes oral herpes while HSV-2 typically causes genital herpes, though either type can cause infection in either area. The virus is usually spread through skin-to-skin contact and can remain dormant in the body between outbreaks. While most infections are asymptomatic, symptomatic infections cause lesions and sores that can be treated but not cured.