Characteristics of the Critical Path
As the project manager, you want to make the best use of your time. The critical path method helps you do that by focusing your attention on the activities that must start and finish on time or else the project will be late. All the activities that have zero total float are on the critical path. If any of them starts or finishes late, then the whole project will be late. Every project will have at least one critical path that runs from the Start node to the Finish node.
The critical path of a project is the longest path in the network; therefore, it determines the earliest completion date of the project. In the following example, the critical path runs through tasks A, C, G, and H. This path is the one with no float, and it is the longest path through the project. It represents the shortest time period in which the project can be completed: 19 days.
The critical path might change as your project progresses; for example, if another path within your project has a total float of 1 day and is delayed by 2 days, that path might now become the critical path.
Sometimes a project has multiple critical paths. This can increase the risk of missing the project's completion date because there is more than one path that has no float in the schedule. If you do not know where the critical paths are, the risk is much higher that you will not meet your schedule.
In summary, the critical path is: