These are the lifecycle, the process groups, and the knowledge areas. Each dimension is unique, although related and interdependent. The project life cycle is the big picture. The life cycle divides the project into a series of phases which provides better project control. The four common phases in a project life cycle are concept, development, implementation, and termination or closeout.
Phases are easy to recognize.
The delivery or completion of a major deliverable usually characterizes the end of a phase. For instance, a feasibility study or architectural design might conclude the conceptual phase. The developmental phase might conclude with the project plan. The implementation phase would conclude with the completion of the product or service. Termination might conclude with the customer sign-off, completion of a lessons learned database, and collection of any historical documentation.