HIV or human immunodeficiency virus is the cause of HIV/AIDS. It is a retrovirus, which infects the human immune system, particularly the CD4+ T cells, macrophages and dendritic cells. HIV is of two types- HIV-1 and HIV-2. HIV-1 is more infective and virulent. It causes the majority of HIV infections worldwide. HIV-2 is comparatively less pathogenic than HIV-1 and has lower transmission rates. However, both lead to AIDS in individuals and also mutate to develop drug resistance. Once HIV enters the body, it undergoes a period of rapid viral replication, which then reduces CD4+ T cells. This results in a weakening of the immune system, thus allowing opportunistic infections to occur. The treatment of AIDS aims at slowing the progression of the disease, using antiretroviral therapy. This therapy consists of a combination of at least two classes of antiretroviral agents, non-nucleoside reverse transcriptase inhibitor and nucleoside analog reverse transcriptase inhibitors. This book covers in detail some existing theories and innovative concepts revolving around HIV medicine. Different approaches, evaluations, methodologies and advanced studies on HIV/AIDS and its management have been included herein. A number of latest researches have been included to keep the readers up-to-date with the global concepts in this area of study.