A project comprise of a series of phases and activities. A method to harness the entire effort, throughout various stages of project is planning. It defines the activities involved in the project and establishes logical sequence and inter-relationship between activities. Accordingly, a schedule is organized to place the project activities on a working timetable.

Planning is essential to perform a function with minimum wastage of time and effort. The schedule is considered as valuable to the planning phase to guide and monitor performance and control over a set of activities to ensure completion of project at required time. A CPM based schedule prepared at beginning of the project identifies activities critical for achieving timely project completion.