The varicella-zoster virus (VZV) causes two diseases. The primary VZV infection, known as chickenpox, typically occurs during childhood. Herpes zoster infection results later in life from reactivation of VZV in the dorsal root ganglia. Herpes zoster characteristically results in a rash with a unilateral dermatomal distribution, which usually resolves within 2 to 4 weeks. If the infection does not resolve after its acute phase, long-term complications, such as postherpetic neuralgia, may develop. The author discusses the natural history and incidence of primary VZV infection and herpes zoster and details the epidemiology, clinical manifestation, diagnosis, and complications of this disease.