AIDS is the common acronym for the human disease Acquired Immune Deficiency Syndrome, or Acquired Immunodeficiency Syndrome. It is characterized by damage to the human immune system, allowing infections that would otherwise be controlled by the immune system to run riot. These infections, the so-called 'opportunistic infections', would be relatively minor to someone with a strong immune system, but can lead to death for AIDS sufferers.

AIDS itself is caused by a virus, the Human Immunodeficiency Virus (HIV), and people who are infected with HIV will develop AIDS over a period of years. The length of time between infection with HIV and the development of AIDS is currently being lengthened by drug regimens, but even before AIDS was identified, one could become infected with HIV and not develop AIDS for several years. This time lag meant that those infected with HIV had a number of years during which they might unwittingly infect others.

The HIV virus is transmitted through bodily fluids, notably semen, blood and breast milk. Tears, saliva and sweat may contain the virus, but in such low concentrations that transmission via these fluids is virtually impossible. People are most commonly infected through unprotected sexual intercourse or the sharing of unsterilized needles among intravenous drug-users.

When AIDS was first identified, it was found to cluster in the gay population in California, and for a number of years, AIDS was unfairly stigmatized as a 'gay disease'. AIDS, however, does not discriminate, and in the early years of the AIDS crisis, heterosexuals and child AIDS sufferers were as unfairly stigmatized as gay AIDS sufferers, with some children being forced from their schools.

AIDS is thought to have originated in Sub-Saharan Africa, where it runs rampant today. In Africa, unlike the US, the main route of transmission is heterosexual sex, and AIDS is having an enormously destructive impact on a number of African countries, cutting a swath through the most productive demographic - young, sexually-active adults. An unwillingness to speak frankly about what causes AIDS slowed international reaction to this disease, but some nations are now successfully slowing the spread of AIDS through widespread advocacy of the use of condoms.

In the US, the spread of AIDS has been slowed by education in 'safe sex' and the development of treatments for the HIV-infected that delay the onset of full-blown AIDS. Whereas in the early days, a person diagnosed with HIV had only a few years to live and AIDS was always fatal - one doesn't 'recover' from it - now people are living longer and longer without progressing to AIDS. The concept of 'living with AIDS' is one the world is just starting to get used to, although the drug therapies are expensive and unavailable in poorer countries. While there are drug-resistant strains of the HIV virus out there, AIDS, at least in the US, certainly remains a serious and dangerous disease, but is no longer the death sentence it once was.