The<unk>  is the medical<unk><unk>  used by the United States Centers for Disease Control and Prevention <unk>  to classify HIV disease and infection. The<unk>  is used to allow the government to handle epidemic statistics and define who receives US government assistance.
CDC classification system for HIV infection
WHO disease staging system for HIV infection and disease
WHO Disease Staging System for HIV Infection and Disease in Children
WHO Disease Staging System for HIV Infection and Disease in Adults and Adolescents
HIV disease progression rates
Timeline of HIV/AIDS
Structure and genome of HIV
Current HIV Research