Celiac disease is a common, chronic inflammatory disorder of the small intestine triggered by exposure to gluten in individuals with certain genetic types. This disorder affects people of any age or gender. Although often thought to be European in origin, it is now global in extent. Presentations are variable, from asymptomatic patients to severe malnutrition. Initial detection usually relies on celiac-specific serology, and confirmation often requires intestinal biopsy. There have been substantial increases in prevalence and incidence over the last 2 decades for reasons that are almost certainly environmental but for which there is no clarity as to cause.