PrEP is a daily (or, in some regimens, on-demand) prescription medicine that, when taken as directed, reduces the risk of getting HIV from sex by around 99%. It is for people who do not have HIV but are at ongoing risk of being exposed to it.
PrEP may be appropriate if you have a partner living with HIV, don't consistently use condoms with partners whose status you don't know, have had a recent STI, or share injecting equipment. It does not protect against other STIs or pregnancy, so it is usually combined with condoms and regular testing.
PrEP requires a prescription, a baseline HIV test (you must be HIV-negative to start), and ongoing monitoring with regular check-ups and kidney function tests. Do not self-source or self-dose this medicine. Speak to a licensed doctor or sexual-health clinic to find out whether PrEP is right for you and to arrange the necessary monitoring.