ABSTRACT
A life cycle is a model of a repeatable process, which is the complete life cycle of a system. For a biological system the process starts with conception and ends when the system dies. For a designed system the process starts from the time it is conceived and ends when it is retired. The process is divided into phases or stages; for example, a software development life cycle might be divided into specification, design, coding and assurance. Each phase requires different methods and skills. The phases may overlap and iterate, but usually start in the sequence shown in the life cycle.
