Emergency management generally refers to activities associated with avoiding and responding to natural and human-caused hazards. Emergency management in the United States is highly decentralized and contextual in nature. Multiple jurisdictions as well as a vast number of agencies, nongovernmental organizations, and private sector entities are often involved. In general, emergency management begins locally, but the federal government plays an important role when a state requests assistance. Consequently, the number and type of actors involved in an incident vary tremendously depending on the context and severity of the event. Similarly, the legal framework through which emergency management functions and activities are authorized is also decentralized and stems from multiple authorities. This report provides Members of Congress and their staffs with an introduction to the principles and foundations of federal emergency management in the United States. It examines the activities of several federal agencies, including the Federal Emergency Management Agency (FEMA), the National Guard, Department of Agriculture, Department of Defense, Army Corps of Engineers, Department of Health and Human Services, Department of Housing and Urban Development, Department of Transportation, Environmental Protection Agency, Forest Service, and Small Business Administration. In addition, this report discusses the four phases of emergency management: (1) mitigation, (2) preparedness, (3) response, and (4) recovery; the process for requesting federal assistance for major disasters, emergencies, and fires; and the types of assistance provided through each type of Stafford Act declaration. This report also includes a description of federal-to-state cost shares under the Stafford Act, a discussion on how federal assistance is funded, and the process through which FEMA requests assistance from other federal entities. This report also outlines the frameworks that guide various emergency management activities at the federal and state level, and discusses some of the key federal laws and policies influencing federal emergency management and highlights federal entities that provide assistance to states and localities. Related CRS products examining these issues more in-depth are footnoted in this report. The following sections describe key concepts that undergird federal emergency management. Many of these concepts originated at the state level and are still being put to use by states and localities. Some concepts developed by the states have been modified and/or adopted by the federal government as a national standard. The all-hazards model is based on the idea that there are generic processes and capabilities needed to address most kinds of emergencies and disasters. For example, preparing and responding to an earthquake entails similar activities and capabilities for preparing and responding to an explosion or terrorist bombing. Thus emergency managers can conduct emergency management activities in a more flexible and cost-effective manner than using a standalone, emergency, or disaster-specific program. Another benefit is that carrying out emergency management functions generally involves adaptation, which is a guiding principle of the all-hazards model. Thus preparations and lessons learned associated with one type of event, can often be applied to another type of emergency or disaster scenario. Emergency management functions are managed according to the principles of the National Incident Management System (NIMS). Authorized by Homeland Security Presidential Directive 5 (HSPD-5), NIMS is a preparedness and response management model based on the Incident Command System (ICS). ICS is a command and control model developed by firefighters after the 1970 fires in southern California. The response to the fires was hindered due to duplication of efforts, lack of coordination, and communication problems. ICS standardizes response operations by using similar terminology, communication systems, and organizational structure to eliminate or reduce confusion during a unified response. NIMS uses ICS concepts to establish a response structure that is scalable (capable of growing as more organizations come together to respond to the incident) that can be used by all jurisdictions, agencies, and organizations to ensure a unified response to complex events. State and local governments must be NIMS compliant to be eligible for certain preparedness grants. Emergency management functions are generally grouped into four phases: (1) Mitigation, (2) Preparedness, (3) Response, and (4) Recovery. The grouping of emergency management functions is useful for classifying and conceptualizing activities. Use of the four phases at the state level is not, however, a requirement for grant funding. As discussed later, the federal government uses a framework approach that differs somewhat from the four phases. The following sections provide examples of the types of activities that take place in each phase. While conceptually useful for targeting efforts and resources, the phases of emergency management are not distinct—activities in each phase often overlap. For example, recovery projects often include elements of mitigation (for example, rebuilding structures using current building codes) and response often includes recovery measures (immediate debris removal). The phases are also cyclical in nature—lessons learned from an incident might be applied in preparedness efforts for future emergencies and major disasters. Mitigation activities entail identifying risks and hazards to either substantially reduce or eliminate the impact of an incident usually through structural measures. Mitigation activities often have a long-term or sustained effect and may have an impact on insurance premiums. In many cases, mitigation activities occur in the recovery stage of a major disaster. Some examples of mitigation include: building codes that address risks such as fires, high winds, or earthquakes; zoning rules that restrict construction in floodplains; rebuilding damaged structures with more resilient materials; flood mapping to identify low lying areas and relocating homes and structures located in floodplains and flood prone areas; and dams and levees that help prevent flooding. Preparedness is distinct from mitigation because rather than focusing on eliminating or reducing risks, the general focus of preparedness is to enhance the capacity to respond to an incident by taking steps to ensure personnel and entities are capable of responding to a wide range of potential incidents. Preparedness activities may include: training; planning; procuring resources, such as food, water, and medication stockpiles; intelligence and surveillance activities to identify potential threats; and exercising to assure the adequacy of planning efforts and the use of after-action reports to improve emergency response plans. Response activities are comprised of the immediate actions to save lives, protect property and the environment, and meet basic human needs. Response involves the execution of emergency plans and related actions, and may include: evacuating victims; deployment of response teams, medical stockpiles, and other assets; and establishment of incident command operations. Recovery activities are intended to restore essential services and repair damages caused by the event. Recovery activities may include: the reconstitution of government operations and services (e.g., emergency services, public safety, and schools); housing and services for displaced families and individuals; and replenishment of stockpiles. On March 30, 2011, President Barack Obama issued Presidential Policy Directive 8: National Preparedness (hereinafter PPD-8). PPD-8 superseded Homeland Security Presidential Directive 8 (HSPD-8), which was signed by President George W. Bush on December 17, 2003. Similar to its predecessor, PPD-8 provides a guide as to how the nation, from the federal level to private citizens, can "prevent, protect against, mitigate the effects of, respond to, and recover from those threats that pose the greatest risk to the security of the Nation" including acts of terrorism and other human caused incidents (such as oil spills) as natural disasters. PPD-8 is also intended to meet several "comprehensive preparedness system" requirements in Subtitle C of the Post-Katrina Act. PPD-8 establishes that preparedness objectives are to be accomplished by subdividing emergency management components into a system of integrated, national planning frameworks according to functionality—prevention, protection, mitigation, response, and recovery. The frameworks are intended to assign roles and responsibilities to various federal agencies with mission areas involved with aspects of federal emergency management. These frameworks either exist in various stages of development or have been implemented. The following sections provide brief descriptions of each framework. While the other planning frameworks address natural hazards and disasters as well as human-caused incidents, the focus of the National Prevention Framework is mainly on preventing imminent terrorist threats. As such, upon issue, the National Prevention Framework is to assign roles and responsibilities and coordinate federal agencies involved with intelligence and information sharing, surveillance, providing public information and warnings, as well as other elements that help the federal government identify, discover, or locate terrorist threats. The National Protection Framework, upon issue, would assign roles and responsibilities and coordinate agencies on a wide range of emergency management and homeland security areas, encompassing cyber security, border security, transportation security, and agriculture and food security, among others. In addition, the working draft of the National Protection Framework proposes the use of academic and research centers to develop new protection technologies and establish protection-related curricula and degree programs. The National Mitigation Framework, upon issue, would address capabilities that reduce the loss of life and property by lessening the impact of disasters. The National Mitigation Framework is distinct from the other planning frameworks because most mitigation activities take place at the local level; the role of the federal government in the National Mitigation Framework is not as prominent as with the other planning frameworks. Issued in January 2008, the National Response Framework (NRF) is the successor of two previous response documents, the Federal Response Plan, which was thought to be too narrow in scope, and the National Response Plan, which was found to be problematic for a variety of reasons, including unclear designations and confusing language and jargon. The NRF guides the federal response to natural and human-caused incidents. However, the NRF is not an "operational plan." Rather, it articulates the overarching emergency management principles used to coordinate and conduct a multi-agency and multijurisdictional response to all types of incidents. The NRF is executed through the use of three supplemental annexes consisting of the (1) Emergency Support Functions Annex, (2) Support Annexes, and (3) Incident Annexes.