Let's start with how it is not transmitted. Since the virus cannot survive outside the body, you cannot get it from toilet seats or shared cups or utensils. You can't get it from kissing or from spit, since it's not transmitted in your saliva.
HIV is also not transmitted in sweat or urine. You can't get it from a swimming pool, hot tub, sauna, mosquito or rodent bites, tattoos, or ear/body piercings.
Only four bodily fluids are known to carry HIV in quantities concentrated enough to infect another person: blood, semen, vaginal fluids, and breast milk. That is, unless a person is on HIV treatment and has reached an undetectable viral load. In that case, that person cannot transmit HIV to another person via these four fluids, which is why many HIV-positive women are able to breast feed without transmitting HIV to their children
According to the Centers for Disease Control and Prevention, one of these four fluids from an HIV-positive person must come in contact with a mucous membrane or damaged tissue, or be directly injected into the bloodstream (from a needle or syringe), for HIV transmission to even possibly occur.