The human immunodeficiency virus (HIV) is a lentivirus (a subgroup of retrovirus) that causes HIV infection and over time acquired immunodeficiency syndrome (AIDS). AIDS is a condition in humans in which progressive failure of the immune system allows life-threatening opportunistic infections and cancers to thrive. Without treatment, average survival time after infection with HIV is estimated to be 9 to 11 years, depending on the HIV subtype. Infection with HIV occurs by the transfer of blood, semen, vaginal fluid, pre-ejaculate, or breast milk. Within these bodily fluids, HIV is present as both free virus particles and virus within infected immune cells.

.hiv is a generic top-level domain (gTLD) proposed by the Berlin-based nonprofit dotHIV and owned by Uniregistry as of September 2014. It is the first open charitable gTLD and its ICANN designation states that the domain's operator is precluded from making a profit. Funds raised from .hiv domain sales will initially benefit projects to increase access to HIV/AIDS treatment in Rwanda, South Africa, Turkey, and the United States.