People with HIV who are aware of their status can get HIV treatment (called antiretroviral therapy or ART) and remain healthy for many years. Studies show that the sooner people start treatment after diagnosis, the more they benefit from ART. Treatment with ART reduces the amount of HIV in the blood (called viral load), reduces HIV-related illness, and helps prevent transmission to others. People with HIV who take HIV medicine as prescribed and get and keep an undetectable viral load (or stay virally suppressed) have effectively no risk of transmitting HIV to HIV-negative sex partners. People who get tested and learn they don’t have HIV can also make decisions about sex, drug use, and health care that can protect them from HIV. For people at risk for HIV, taking HIV medicine called pre-exposure prophylaxis (or PrEP) is highly effective for preventing HIV.