This video is an overview of autoimmune disease. Autoimmune disease causes your immune system to attack healthy tissue and cells instead of harmful substances. Harmful substances contain antigens that allow the immune system to recognize these substances and destroy them. Sometimes these substances can confuse the immune system, as the immune system may not be able to distinguish between healthy tissue and antigens. This video was created by high-school students Hamza Khan (Hillfield Strathallan College), Kate Kim and Chris Chois (Notre Dame High School) in collaboration with the McMaster Demystifying Medicine Program and Khatija Anum.