Why critical path is critical to project management?

Critical path method - This is the schedule network analysis technique used to identify the schedule flexibility and the critical path of the project schedule network diagram. The critical path is the longest path (sequence of activities) in a project schedule network diagram. Because it is the longest path, it determines the duration of the project and hence the finish date of the project given the start date

The Critical Path and Duration of the Critical Path, gives the project manager a clear picture of how long all the activities can take to complete. It also helps him to identify the flexibility in the project schedule by calculating the early and late start and finish dates of each activity on each path. The schedule flexibility of an activity is measured by the positive difference between the late start date and the early start date for the activity and is called float time or total float.