Over the years there has been considerable confusion with the concepts of safety, risk, and hazard. The major problem is that many people tend to interchange the words as if they mean the same. On top of that, different industries often define the concepts differently.
The system is the combination or interrelation of hardware, software, people, and the operating environment. In system safety engineering you must look at the system from cradle to grave. In other words, the system life cycle is the design, development, test, production, operation, and retirement (or disposal) of the system.