In project management, the critical path is the longest sequence of dependent tasks that determines a project’s minimum duration.
The critical path method represents a project as connected activities with estimated durations and dependencies. By calculating the earliest and latest possible times for each activity, managers can identify the chain with the greatest total duration. A delay to an activity on that chain can delay the project’s completion unless the schedule is changed.
Activities outside the critical path may have float, also called slack. Float is the amount of time an activity can slip without delaying a specified milestone or the entire project. The critical path can change during execution if task durations, dependencies, or resources change, so it is not necessarily fixed at the planning stage.
A critical path is not simply the list of the most expensive or important tasks. It is a schedule concept based on dependency and timing. Projects can also have more than one critical path when separate chains have equal total duration.