The human immunodeficiency virus (HIV) causes HIV infection, which later develops into acquired immunodeficiency syndrome (AIDS). This condition leads to a progressive failure of the immune system which allows certain life-threatening, opportunistic infections and cancers to affect the body. HIV infection may be transmitted sexually such as by contact with vaginal fluids, semen or pre-ejaculate. It may also be transferred from an infected mother to child during pregnancy and childbirth, through breast milk, contaminated blood transfer, etc. HIV infects the helper T cells, macrophages and dendritic cells of the human immune system. Such infection results in low levels of CD4+ T cells through various mechanisms. When these cells decline below a critical level, cell-mediated immunity is lost and the body becomes susceptible to opportunistic infections. There is no effective vaccine or cure for HIV/AIDS. Treatment strategies attempt to slow the progression of the disease with highly active antiretroviral therapy and manage the occurrence of opportunistic infections. A healthy diet is generally promoted for the management of AIDS. This book is a valuable compilation of topics, ranging from the basic to the most complex advancements in the understanding of HIV/AIDS. From theories to research to practical applications, case studies related to all contemporary topics of relevance to this infection have been included herein. It is appropriate for students seeking detailed information in this area as well as for experts.