What does critical pressure refer to?

Critical pressure refers to the lowest pressure at which a substance can exist as a liquid at the critical temperature. At the critical temperature, the properties of the liquid and gas phases become indistinguishable, and any attempt to increase pressure at this temperature will not lead to the formation of a liquid phase unless the pressure reaches or exceeds the critical pressure. This concept is crucial in understanding phase transitions and the behavior of substances under extreme conditions.

In the context of this question, understanding critical pressure is important in fields such as thermodynamics and physical chemistry, where the behavior of materials under various temperatures and pressures is studied.