Risk can be expressed as the probability of a particular event multiplied by the consequences faced; i.e. the probable loss (or benefit) when performing a particular activity in a hazardous environment:

Risk = probability * consequences

Probability: the probability of the triggering natural event to occur (hazard: earthquake, storm, flood, drought etc.)
Consequences: potential loss or benefit

In DRR terms (disaster risks): The potential disaster losses, in lives, health status, livelihoods, assets and services, which could occur to a particular community or society over some specified future time period, caused by a natural event or a technical failure.

(Disaster) risk = Hazard * Vulnerability / Coping Capacity

Consequently, disaster risk reduction is "the concept and practice of reducing disaster risks through systematic efforts to analyse and manage the causal factors of disasters, including through reduced exposure to hazards, lessened vulnerability of people and property, wise management of land and the environment, and improved preparedness for adverse events".

In short, DRR aims to:

• Avoid human losses (dead, injured, homeless)
• Prevent economic damage (private assets, public infrastructure)
• Secure livelihood (household, community, business)