Risk and vulnerability are often used interchangeably: however, in some contexts, the terms have related but separate meanings.  While risk is often used to describe the likelihood of an event happening, vulnerability may refer to, for instance, the quality of controls in a system that affect the ability of the system to withstand an event or to the economic significance of the impact of the event.  As an example, there may be a risk in the supply chain if the sole manufacturer experiences an interruption to production.  If the pipeline stock in the supply chain is insufficient to cover requirements until the manufacturer can resume production, then the whole supply chain is vulnerable.  See also Risk and Uncertainty.