Mass casualty incidents (MCIs) occur when the number of casualties exceeds available healthcare resources, requiring a shift from individual patient-centered care to utilitarian allocation of resources for the greatest good. The START (Simple Triage and Rapid Treatment) triage system categorizes patients in under 60 seconds based on respiratory rate, perfusion (radial pulse or capillary refill), and mental status (follows commands). Disaster phases include mitigation (prevention), preparedness (planning and training), response (acute event management), and recovery (restoration). In MCIs, the standard of care shifts from individual optimization to allocation-based decision making. The incident command system (ICS) provides a standardized organizational structure with defined roles: Incident Commander, Operations, Planning, Logistics, and Finance/Administration. Surge capacity refers to a healthcare facility's ability to expand beyond normal operations through space (additional treatment areas), staff (recall of off-duty personnel), and stuff (equipment and supply reserves). Crisis standards of care, activated during declared disasters, provide legal and ethical frameworks for resource allocation decisions, including ventilator triage protocols.