A task that must be completed on schedule for the project to finish on time. If a critical task is delayed, the project completion date is also delayed. In a typical project, many tasks have some slack time and can therefore be delayed a bit without delaying other tasks or affecting the project end date.

If a WBS item cannot be delayed without affecting the project end date, it is called a critical WBS item. A WBS item is critical if it meets any one of the following conditions:

A critical WBS item is identified by this symbol:

You can choose to turn on or turn off the critical path indicator by clicking the Show critical path / Hide critical path toggle button on the toolbar at Project items.