A hazard is a situation that poses a level of threat to life, health, property, or environment. Most hazards are dormant or potential, with only a theoretical risk of harm; however, once a hazard becomes "active", it can create an emergency. A hazardous situation that has come to pass is called an incident. Hazard and possibility interact together to create risk.

A hazard is an event posing a threat to life, health, property or environment. For hazards in the context of risk assessment, see Hazard (risk).