Used primarily in the treatment and prevention of HIV infection. It works by inhibiting the viral reverse transcriptase enzyme, reducing the amount of virus in the body. Commonly prescribed as part of antiretroviral therapy (ART), it helps slow disease progression and lowers the risk of transmission. Also effective against hepatitis B virus (HBV) and used in managing chronic HBV infection. Available in oral formulations, including combinations with other antiretrovirals for simplified dosing. Widely used in pre-exposure prophylaxis (PrEP) to protect high-risk individuals from acquiring HIV.