A disaster is a sudden, calamitous event that seriously disrupts the functioning of a community or society and causes human, material, and economic or environmental losses that exceed the community's or society's ability to cope using its own resources. Though often caused by nature, disasters can have human origins.

Rehabilitation, reconstruction and sustainable recovery refer to measures that help restore the livelihoods, assets and production levels of emergency-affected communities. These measures rebuild essential infrastructure, institutions, services and restore the means of production destroyed or made non-operational by a disaster.

Rehabilitation and reconstruction assistance is geared towards limiting the need for relief and allowing development activities to proceed. Rehabilitation and reconstruction include measures which help increase the resilience of food systems in case of future disasters and emergencies. Major emphasis is on strengthening co-ordination of locally active emergency and development institutions and on encouraging the participation of the affected population in designing and implementing interventions to promote household food security and nutrition. Priority is given to the needs of food-insecure households and towards promoting sustainable livelihoods.