An Automated External Defibrillator (AED) is a portable medical device that can detect life-threatening heart rhythms and deliver an electric shock to restore normal heartbeat during sudden cardiac arrest. AEDs are designed to be used by ordinary people with minimal training—the device provides voice instructions and will only deliver a shock if it detects a rhythm that can be corrected. Many municipalities require AEDs in public buildings, recreation centres, schools, and other facilities as part of their emergency preparedness. Some provinces mandate AED placement and registration. Having accessible AEDs is a public safety investment that can save lives in the crucial minutes before paramedics arrive.