1. Herpes simplex virus is a double-stranded DNA virus that causes a variety of diseases through infection of mucosal surfaces. It has two types, HSV-1 and HSV-2, which can cause oral and genital lesions, respectively. 2. HSV infections are common worldwide and are transmitted through direct contact. Primary infections may present with localized lesions and systemic symptoms. Recurrent infections typically cause milder localized symptoms. 3. Diagnosis involves visual identification of lesions as well as laboratory tests to detect viral DNA. Antiviral medications can be used to treat infections and reduce symptoms.