In this module we will be talking more about the critical path and highlight why it is important and how to use it. And try to work together on how to identify the critical path or paths that we have in your project. So before we move forward, let's study this project that we covered in a previous module that focusing and calculating the forward and the backward past calculations, or the CPM forward and backward task calculations. If you remembered, we had the following activities. And I want you to look at what sequence of activities or how many sequence of activities we do have in this project. If you would notice here we do have activity A, B, E, and G. This is one path to go through the entire schedule of the project. Another sequence of activities to go from the start to the finish of the project would be A, C E and G, this is the second path. A third path will be A, C, F, and G. And the last path we can go from start to the finish of my project here would be A, D and G. So if I ask you to calculate the duration on all of these path, we get the following. ABEG will have 18 days long, the total duration of that path, the ACEG 15 days, ACFG 12 and ADG is 15. So the longest path duration we have would be A, B, E and G of 18 days. All the other activity sequence from the start to the finish of the project will generate, as we see here, a shorter total duration. Also, if you recall by performing the forward pass calculations, we can find the duration of the project. However, the backward pass calculations make it easier for us to identify the longest path of activities at our project, as we saw here. Moreover, we notice also that all activities that are at the longest path has an early start equal its late start, or its early finish equal the late finish. Let's take an example here. The longest path here is what A, B, E and G. The early start for A is 0, the late start also is 0. Early finish is 1, the late finish is 1. Activity B, 1 equal also 1, the early start and the late start. The early finish equal the late finish. Activity E also 10, 10, 17, 17. The last activity on that longest path we have 17 equal 17, the early start equal the late start and the early finish equal the late finish. If you notice all these activities has the same property, so the focus here is that the with the maximum total duration is called the critical path of your construction project. And its activities also called critical activities. This critical path is very important when it comes to control your construction of project. Also, understanding its implications is very essential for a rational management decisions. So again, if I want to define it, that critical path, there is different definitions. But the main definition I want you to remember and take out from this course is the path with the maximum total duration in your project. Now let me explain in more details about some properties of critical path and to also come into conclusion why it is important. So here we highlighted this is the critical path in yellow.