Herpes simplex virus 1 (HSV-1) is a common virus that primarily causes oral herpes, which is characterized by cold sores or fever blisters that appear around the mouth or on the face. It belongs to the genus Simplexvirus, subfamily Alphaherpesvirinae, and family Herpesviridae. HSV-1 is highly contagious and usually acquired during childhood through oral contact, such as kissing or sharing utensils. It can also be sexually transmitted through oral- genital contact. After initial infection, HSV-1 establishes latency in nerve cells, particularly in the trigeminal ganglia, and can reactivate later, causing recurrent outbreaks. Symptoms of HSV-1 infection range from being asymptomatic to causing painful grouped vesicles (cold sores) on an erythematous base, which eventually crust over and heal. Besides oral herpes, HSV-1 can cause other conditions such as herpetic whitlow (finger infection), ocular herpes (eye infection that can lead to blindness), and in severe cases, herpes encephalitis, a life-threatening brain infection. Globally, about 67% of people under age 50 are estimated to have HSV-1. The virus can evade the immune system and persist lifelong in the body, with episodes of reactivation leading to contagious viral shedding. There is no cure for HSV-1, but antiviral therapies can help reduce the severity and frequency of outbreaks.