Carbon dioxide is the gas produced by the human body during respiration. When we inhale, oxygen is taken into the lungs and transported to cells throughout the body. These cells use oxygen to break down glucose and produce energy, releasing carbon dioxide as a byproduct. This carbon dioxide is then transported back to the lungs, where it is exhaled. The exchange of gases—oxygen in and carbon dioxide out—is vital for our survival and plays a crucial role in cellular respiration, the process by which our cells generate the energy needed for various bodily functions.