HIV (Human Immunodeficiency Virus) mainly spreads through unprotected sexual contact with an infected person when body fluids such as blood, semen, vaginal fluids, or rectal fluids enter the body through mucous membranes or small cuts. The risk is higher if protection is not used or if either partner has other sexually transmitted infections. To prevent infection, it is important to use condoms correctly every time during sex, limit the number of sexual partners, get regular HIV and STI testing, and ensure that both partners know their HIV status. Avoid sharing needles or sharp instruments. If someone is at higher risk, doctors may also recommend preventive medicines such as pre-exposure prophylaxis (PrEP). Practicing safe sex and regular testing are the most effective ways to reduce the risk of HIV infection.