Critical Path is the sequence of activities for which the slightest delay will influence the end of the project. The critical path of a project may change in time according to the new changes of the project schedule. In a project there can be several critical paths. Tasks that compose the critical path are called critical tasks.
Critical tasks need a special attention as they are more likely to compromise the completion date. Sometimes the project manager needes to see those tasks that could delay the project finish if they are late with a certain amount of time, in other words the tasks with a slack smaller than a given value.
In RationalPlan Project Management Software the Critical Path can be displayed by pressing the corresponding button from the toolbar while in Gantt view.