To detect whether you have AIDS, you can have a blood test for HIV antibodies. If you have not had any risky sexual behavior recently and have not been infected with AIDS, you can use the 3rd generation test, which only tests for HIV antibodies. If the test is negative, you can basically rule out the possibility of being an AIDS patient; if it is positive, you still need to be retested, because such a test has a certain false positive rate, and a positive test once is not 100% sure that you are an AIDS patient. If you have recently had a risky contact, you may be infected with HIV and can be retested after the window period. The 4th generation test is based on the 3rd generation, and in combination with the P24 antigen test on top of the HIV antibody, you can completely rule out the possibility that you have AIDS after 6 weeks. So in this case, after 6 weeks, the 4th generation test can be used and if the result is negative, you can rule out the possibility of being infected with AIDS.