The word “safety” has a variety of meanings. It is a condition of being free from “accidents,” or any device for preventing an accident. The word “accident” means “unintended event,” and does not reveal that there is a cause created by a “hazard.” In many people’s minds, an “accident” is the result of someone’s failure to avoid or prevent a dangerous condition or circumstance. It is often assumed that all one needs to do is just “be safe.” Overlooked is that “hazards” are not obvious to everyone all of the time. It is a fact that as machines and systems become increasingly complex, many hazards are hidden. The evolution of safety is the transition of “behavior-based safety” to “design-based safety.