HIV/AIDS is without doubt the worst epidemic to hit humankind since theBlack Death. The first case was identified in 1981; by 2004 it was estimatedthat about 40 million people were living with the disease, and about 20 millionhad died. Despite rapid scientific advances there is still no cure and the drugs areexpensive and toxic. Because of controversies and taboos surrounding safe drugusage and prostitution, the numbers of people infected continues to rise.However, it is in the developing world and especially parts of Africa that thereal catastrophe is unfolding. In some of the worst affected countries lifeexpectancy has plummeted to below 35 years, which has led to a serious declinein economic growth, a sharp rise in orphaning, and the imminent collapse ofhealth care systems. The news is not all bleak though. There have been unprecedented breakthroughs inunderstanding diseases and developing drugs. Because the disease is so closelylinked to sexual activity and drug use, the need to understand and changebehaviour has caused us to reassess what it means to be human and how we shouldoperate in the globalising world. This iVery Short Introduction/i provides anintroduction to the disease, tackling the science, the international and localpolitics, the fascinating demographics, and the devastating consequences of thedisease, and explores how we have -- and must -- respond.