 Let us now look at a special type of process known as a cycle. Of course, since we are in thermodynamic, this is a thermodynamic cycle. We have studied processes as a change of state. So we have an initial state and a final state. If it turns out that the initial state i and the final state f are the same, then that process is known as a cycle, process for which the initial state and final state are the same. So the minimal representation of a cycle would be something like this, simply a dot in the state space of the system in what? Indicating both the initial state as well as the final state. However, it is possible that as the process is executed, the system goes away from the initial state takes a very scenic route and comes back to the initial state and says, well, this is also my final state. So if it executes a cycle in a quasi-static way, so we will get perhaps a cycle like this. This is the depiction of a quasi-static cycle. So let me label it as A. So A is a quasi-static cycle. I can have another quasi-static cycle. Let me call it B. B is another quasi-static cycle. If you consider A throughout the process, the state was known because it was a state of equilibrium. But one could have, I will create another figure so as not to increase the clutter. Let us say this is the initial state as well as the final state and then let us say that the system takes some process but no state during that cyclic process is a state of equilibrium. So here is the depiction of a non-quasi-static cycle. Notice that this visual representation of the cycle by means of a dotted line is just a representation. The location of the dotted line does not mean anything. But whenever we have a quasi-static cycle, it is represented by a proper closed loop in the thermodynamic state space. Thank you.