There have been spectacular gains made in the battle against HIV and the disease it causes, AIDS, but it remains one of the world’s biggest killers. Follow the path of this virus from its origins in Africa, to its emergence as the cause of a frightening epidemic, to its status as a treatable but incurable condition. There are timelines on the important dates in the history of HIV and on celebrity deaths. Among the sidebars are one on a young man whose death got congress to fund programs to help people with HIV, and one on the only man ever cured of AIDS.