In emergency management, assessment means collecting subjective and objective information in order to measure damage and identify those basic needs of the affected population that require immediate response. The assessment is always meant to be rapid, as it must be performed in limited time, during or in the immediate aftermath of an emergency.

At the onset of a crisis, rapid assessment information will be used to recognize and quantify the emergency, and to readjust strategies and plans accordingly. Once a programme of assistance is under way, periodic assessments will assist evaluation of the effectiveness of response and recovery. In a wider perspective, rapid assessment will produce information for financial and political advocacy, public information, press releases, and case studies.

The information produced by the assessment is both an asset and a commodity. It must be used for vital decision-making, and for feedback along the different levels of the health sector. But this information can also be marketed to other sectors. Mutual exchange of information is the first step in effective coordination, and being recognized as a reliable source of information is the best way for an organization to assert its claim to a coordinating role.

The purpose of a rapid assessment is to:

- confirm the emergency;
- describe the type, impact and possible evolution of the emergency;
- measure its present and potential health impact;
- assess the adequacy of existing response capacity and immediate additional needs; and
- recommend priority action for immediate response.