Herpes is a viral infection caused by the herpes simplex virus (HSV). There are two main types of the virus, HSV-1 and HSV-2. HSV-1 generally causes oral herpes presenting as fever blisters or cold sores on or around the mouth. It may also cause genital herpes, which may occur from oral-genital contact during an HSV infection. HSV-2 is the most common cause of genital herpes, but it can cause oral herpes too. You can also get herpes anywhere on your skin. Depending on how you come in contact with the virus, either type can cause outbreaks near the mouth or on or near the sex organs.