What is HIV?

HIV (human immunodeficiency virus) is a virus that attacks the immune system. Your immune system protects you from germs and infections to keep you from getting sick. Once HIV is in your system, it lowers the number of healthy immune cells that you have to fight germs and infections.

When the number of healthy cells drops past a certain amount (200 cells per cubic millimeter of blood or less) and you can get certain infections (called opportunistic infections), this is known as AIDS (acquired immune deficiency syndrome). For some people it takes a long time for AIDS to develop, for others it takes less time.