A viral illness known as HIV infection targets the immune system, most especially the CD4 cells (T cells), which are essential for the body's defense against infections and illnesses. HIV can spread through the sharing of specific body fluids, including breast milk, semen, blood, and vaginal secretions. For the purposes of therapy and prevention, it is essential to comprehend the course and effects of HIV infection.Many sufferers of the first infection have flu-like symptoms, including fever, rash, sore throat, and enlarged lymph nodes. Some individuals, meanwhile, might not show any symptoms at all throughout this initial phase. Following this initial stage, the virus goes into a dormant state, where it replicates more slowly and might not show symptoms for years. HIV continues to be active during this period and gradually impairs immunity. The body becomes more vulnerable to different infections and specific cancers as the virus multiplies and the immune system deteriorates. HIV infection advances to the most advanced stage, acquired immunodeficiency syndrome (AIDS), when the immune system is seriously compromised.When the number of CD4 cells per milliliter of blood falls below 200 (a normal count is between 500 and 1,600 cells per millimeter), AIDS is diagnosed. People are more vulnerable to opportunistic infections and certain cancers that a robust immune system would typically be able to prevent at this point because the body is unable to fight off infections. Antiretroviral therapy (ART) has greatly advanced HIV treatment. With ART, a number of drugs are taken in combination to suppress the virus and promote the immune system's healing and efficiency. When taken appropriately and consistently, antiretroviral therapy (ART) can significantly extend the life expectancy of those living with HIV, stop the virus from progressing to AIDS, and lower the risk of viral transmission.The prevention of HIV infection is still essential. This entails having safe sexual relations, using condoms, getting tested for HIV, finding out one's status, and not sharing needles. For those who are highly susceptible to contracting HIV, pre-exposure prophylaxis, or PrEP, is an additional option. In summary, HIV infection is a dangerous illness that compromises immunity and, if untreated, can result in AIDS. However, the effects of HIV can be reduced and those who with the virus can live long, healthy lives with early diagnosis, treatment, and prevention.