It protects and defends us against all manner of diseases — pathogens, parasites, bacteria and other bugs.
But sometimes our immune system can become overactive, attacking our body's own healthy cells, tissues and organs under the mistaken impression that they somehow pose a threat.
This is what happens for people living with an autoimmune disease.
Autoimmune diseases can primarily impact either one main organ, like type 1 diabetes which affects the pancreas, or several organs in the case of systemic autoimmune diseases like lupus or rheumatoid arthritis.
The Australasian Society of Clinical Immunology and Allergy says there are more than 80 related disorders that fall under the banner of autoimmune diseases, ranging from common to rare.
Between three to eight percent of the population are affected by autoimmune diseases globally, although they occur in women at double the rate they occur in men and are also a leading cause of death for women under the age of 65.
The evidence suggests the prevalence of autoimmune diseases overall is increasing, posing significant public health challenges.
It's been estimated that one in five of us will develop an autoimmune disease at some stage of our lives.
Currently, there are no cures for any autoimmune diseases but researchers hope that may soon change.
