Partial pressure refers to the pressure exerted by a specific gas in a mixture of gases. It is a crucial concept in understanding how gases behave, particularly in relation to Dalton's Law, which states that the total pressure of a gas mixture is the sum of the partial pressures of each individual gas. In practical terms, partial pressure helps explain how gases like oxygen and carbon dioxide move in and out of the bloodstream in the lungs. Each gas's partial pressure influences its diffusion, allowing for essential processes like respiration to occur efficiently.