Vulnerability refers to "the quality or state of being exposed to the possibility of being attacked or harmed, either physically or emotionally."[1]

A window of vulnerability (WOV) is a time frame within which defensive measures are diminished, compromised, or lacking.[2]

The understanding of social and environmental vulnerability, as a methodological approach, involves the analysis of the risks and assets of disadvantaged groups, such as the elderly. The approach of vulnerability in itself brings great expectations of social policy and gerontological planning.[3][4] Types of vulnerability include social, cognitive, environmental, emotional or military.

In relation to hazards and disasters, vulnerability is a concept that links the relationship that people have with their environment to social forces and institutions and the cultural values that sustain and contest them. “The concept of vulnerability expresses the multi-dimensionality of disasters by focusing attention on the totality of relationships in a given social situation which constitute a condition that, in combination with environmental forces, produces a disaster”.[5] It is also the extent to which changes could harm a system, or to which the community can be affected by the impact of a hazard or exposed to the possibility of being attacked or harmed, either physically or emotionally.

Within the body of literature related to vulnerability, one major research stream includes the methodology behind said research, namely measuring and assessing indicators of vulnerability. These include external—sudden shocks and continued stresses—and internal indicators, such as defenselessness or inability to cope with incapacities.[6] Vulnerability research covers a complex, multidisciplinary field including development and poverty studies, public health, climate studies, studies, engineering, geography, political ecology, and disaster risk management.[7] This research is of importance and interest for organizations trying to reduce vulnerability[8] – especially as related to poverty and other Millennium Development Goals. Many institutions are conducting interdisciplinary research on vulnerability. A forum that brings many of the current researchers on vulnerability together is the Expert Working Group (EWG). Researchers are currently working to refine definitions of “vulnerability”, measurement and assessment methods, and effective communication of research to decision makers.[9][10]