So we're going to describe the mechanism by which ventilation is carried out inside human lungs. Now, let's begin by breaking down the process of ventilation into two stages, into two processes. We have the process of inhalation and the process of exhalation. And these two processes are actually opposite with respect to one another. Inhalation is when we bring air into the lungs. And exhalation is the process by which we expel the air from the lungs into the outside environment.