The HSV IgG test detects the presence of Immunoglobulin G (IgG) antibodies specific to Herpes Simplex Virus types 1 and 2 in the blood. IgG antibodies indicate past or long-term infection, rather than an active or recent infection.

HSV-1 is commonly associated with oral herpes, causing cold sores around the mouth. 
HSV-2 is primarily linked to genital herpes.