What is AIDS?
AIDS stands for Acquired Immunodeficiency Syndrome. AIDS is caused by the Human Immunodeficiency Virus (HIV). HIV attacks and destroys CD4 cells, the disease-fighting cells of the immune system. As the immune system is seriously damaged, the infected person is more vulnerable to certain cancers and a wide range of infections. These types of infections are known as opportunistic infections because they take advantage of a person's weakened immune system and normally do not attack healthy people.