HIV antigens and antibodies are substances that may be produced by the body after HIV infection. There are many kinds of antigens, and the P24 antigen may appear after the initial infection of the body with AIDS, and may be detected from the blood circulation. Antibodies are AIDS antibodies, divided into type 1 and type 2 antibodies, which are related to the specific genotype of HIV infection, and are generally used in the process of testing for AIDS, by drawing blood to test for these things. If HIV antibodies or HIV P24 antigen are detected in a blood test after a period of high-risk sex or exposure to HIV, it can be determined that the person has been infected with HIV, but this determination is not 100%, because such a test has a certain false positive rate and a confirmatory test is still needed. If the antigen and antibody are negative after the window period, the possibility of HIV infection can be ruled out.