Human immunodeficiency virus (HIV) is a type of virus that infects humans and over time causes acquired immunodeficiency syndrome (AIDS), which facilitates cancers and opportunistic infections to thrive due to the immune system failure. Acute infection, clinical latency and AIDS are the three stages of HIV infection. Unprotected sex, contaminated blood transfusions, hypodermic needles, and transmission from mother to child during pregnancy are the most common ways in which HIV is transmitted. It has been classified into two types and includes HIV-1 and HIV-2. Preventative measures of HIV infection include safe sex, needle exchange programs, and pre and post-exposure prophylaxis. Antiretroviral medications are typically used in the treatment of HIV in order to control the infection. This book explores all the important aspects of HIV infection in the present day scenario. It aims to serve as a resource guide for students and experts alike and contribute to the study of this medical condition. The book also aims to shed light on some of the unexplored aspects of the treatment and prevention of HIV.