The scientific principle that describes how gases behave at varying temperatures and pressures is known as the gas law. This encompasses several laws, including Boyle's Law and Charles's Law. Boyle's Law states that the pressure of a gas is inversely proportional to its volume at a constant temperature, while Charles's Law posits that gas volume is directly proportional to its temperature at a constant pressure. Together, these laws explain the physical properties and behavior of gases under different conditions.