The science of autoinflammatory diseases has progressed rapidly since the term was first coined in the late 1990s in an effort to distinguish this distinct group of illnesses from the more well-defined autoimmune diseases, such as rheumatoid arthritis and lupus. Advances in genetic technologies have expanded the understanding of the molecular and cellular basis of autoinflammatory diseases and have broadened the field to include disorders that no longer fit within the original classification.