Critical Path – The below diagram depicts the critical path for a given project. Critical path analysis is a widely-used project management tool for scheduling projects and allows to see which actions impact the overall schedule.
In project management, a critical path is the sequence of project activities which show the longest overall duration of the project and thus the shortest time possible to finish it. Critical path activities have 0 slack (or float), i.e. one cannot be late on any of these activities without delaying the whole project.
A simple example of the critical path: imagine you need to take your car to a mechanic and the repair takes 2 hours. In those 2 hours, you need to walk to the nearby store and purchase some gifts, which should take you no more than an hour. Afterwards you are going to a party and you don’t want to be late to. Mechanic’s work is on the critical path, i.e. if it takes more than 2 hours, you are going to be late to the party. Gift shopping is not on the critical path, even though it is still required. There is slack of about 1 hour because you are waiting for the mechanic.
The example below also shows a critical path with black arrows and non-critical path with light blue arrows. Duration of each activity and individual paths is also shown on the diagram.