HIV (Human Immunodeficiency Virus) is a virus which affects us and when it affects us we are stuck with it for the rest of our life. We can still lead a normal and healthy life if we keep the number of HIV virus very low. It means that the low amount of virus cannot kill enough of our white blood cells in the body which fight infection for us. If we do not do anything about the HIV virus, then it starts multiplying and attacks CD4+ T cells and it destroys them and when our CD4+ T cells number falls below a threshold, then we become prone to different kind of infections, which we really never get in our normal day-to-day life. At that time, a combination of all those infections and their symptoms is called a syndrome- ‘Acquired Immune Deficiency Syndrome’.