Human immunodeficiency virus (HIV) infection and acquired immunodeficiency syndrome (AIDS) are pandemic and pose one of the greatest challenges to global public health. As a bloodborne and sexually transmitted infection, HIV has variable patterns of transmission and impact among world regions and has disproportionately affected disadvantaged or marginalized persons such as commercial sex workers, injection drug users, men who have sex with men (MSM), and persons living in poverty. HIV infection has caused approximately 20 million deaths; an estimated 36 million persons are infected (Figure 1). On the basis of data from the Joint United Nations Program on AIDS (UNAIDS) and other sources, this report summarizes epidemiologic trends, highlights several HIV and AIDS prevention milestones, and describes some prevention activities for the coming decade.