Human Immunodeficiency Virus belongs to the Retroviridae family. HIV is a lentivirus, a subgroup of retrovirus. HIV virus causes HIV infection and if left untreated, over a time leads to the Acquired Immunodeficiency Syndrome (AIDS). HIV weakens the immune system by destroying white cells (CD4+ T cells). HIV infection doesn’t mean the AIDS disease. HIV cannot be eliminated completely from the human body. Complete cure for HIV is not available but it can be controlled with proper treatment. AIDS is a final stage where immune system is in a worse condition and unable to defend from getting attacked by different diseases. Correct and appropriate treatment to HIV at early stage can prevent from developing of AIDS disease to a larger extent.