HIV gains access to the body through open cuts, sores, or breaks in the skin; through mucous membranes, such as those inside the anus or vagina; or through direct injection. This can happen through:
Sexual contact with an infected person.
Sharing needles, syringes, or other injection equipment with someone who is infected.
Mother-to-child transmission. Babies born to HIV-positive women can be infected with the virus before or during birth, or through breastfeeding after birth.
Transmission in health care settings. Healthcare professionals have been infected with HIV in the workplace, usually after being stuck with needles or sharp objects containing HIV-infected blood.
Transmission via donated blood or blood clotting factors. However, this is now very rare in countries where blood is screened for HIV antibodies, including in the United States.

Common myths about how HIV is spread
These are some of the circumstances you don't have to worry about because they will not put you at risk for becoming infected with HIV:
Being bitten by a mosquito or other bugs, being bitten by an animal.
Eating food handled, prepared or served by somebody who is HIV positive.
Sharing toilets, telephones or clothing.
Sharing forks, spoons, knives, or drinking glasses.
Touching, hugging or kissing a person who is HIV positive.
Attending school, church, restaurants, shopping malls or other public places where there are HIV-positive people.

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