When discussing a life cycle, you can distinguish between a system life cycle and a project life cycle. The project life cycle encompasses all the activities of a project, how a project is planned, designed, developed, and tested and covers from inception to completion for a specific project. The project life cycle is a subset of the larger system life cycle which begins with the operations planning that leads to the need for a system all the way through to the operation, update, and finally retirement or replacement of the system. The diagram below uses the simplified Vee model to illustrate the difference between a project life cycle and the overall life cycle of a system. Note that a system may have one or more projects that are implemented to form the entire system.
