HIV is a retrovirus

HIV is an enveloped retrovirus. Each virus particle contains two copies of an RNA genome. The virus also has a number of enzymes: reverse transcriptase, integrase and viral protease. These molecules play an important role in making new copies of HIV and can be the targets of antiretroviral drugs. The HIV viral particle, or virion, has a capsid which is cone-shaped and is enclosed in a lipid bilayer, or envelope. This envelope contains viral glycoproteins which bind specifically to CD4 T cell receptors, enabling the virus to enter its host.

The name retrovirus comes from the fact that the RNA genome is transcribed/copied back into DNA in the host cell (by reverse transcriptase). The DNA is then incorporated into the host cell chromosome.

HIV belongs to a group of retroviruses called lentiviruses, from the Latin lentus, meaning slow, because of the gradual course of the disease they cause.