The National Incident Management System (NIMS) is a systematic, proactive approach to guide departments and agencies at all levels of government, nongovernmental organizations, and the private sector to work together seamlessly and manage incidents involving all threats and hazards—regardless of cause, size, location, or complexity—in order to reduce loss of life, property and harm to the environment.

The purpose of the NIMS is to provide a common approach for managing incidents. The concepts provide for a flexible but standardized set of incident management practices with emphasis on common principles, a consistent approach to operational structures and supporting mechanisms, and an integrated approach to resource management.

Incidents typically begin and end locally, and they are managed daily at the lowest possible geographical, organizational, and jurisdictional level. There are other instances where success depends on the involvement of multiple jurisdictions, levels of government, functional agencies, and/or emergency-responder disciplines. These instances necessitate effective and efficient coordination across this broad spectrum of organizations and activities. By using NIMS, communities are part of a comprehensive national approach that improves the effectiveness of emergency management and response personnel across the full spectrum of potential threats and hazards (including natural hazards, terrorist activities, and other human-caused disasters) regardless of size or complexity.