This freely-available online medical textbook is written by expert clinicians in Europe and the United States in clear language that will have broad appeal to non-medical readers. Updated every year, it contains searchable information about the clinical manifestations of HIV/AIDS and its treatment, including acute infection, antiretroviral drugs, and drug resistance testing. Rather than going into detail about scientific or medical research, the textbook concentrates on the facts and explanations around HIV/AIDS signs and symptoms.