Biology is the study of life, and uses the scientific method, the basis of science, to do so. Hypotheses are made, tested, and remade, until a theory is made, which then becomes Scientific law.
Most commonly, people get or transmit HIV through sexual behaviors and needle or syringe use. Only certain body fluids—blood, semen , pre-seminal fluid, rectal fluids, vaginal fluids, and breast milk—from a person who has HIV can transmit HIV.
