A perfect gas (which can also be referred to as an ideal gas) is a gas that, in its physical behaviour, perfectly obeys the ideal gas law (which provides a relationship between the pressure exerted by a gas, the volume occupied by the gas, the amount of gaseous substance, and the absolute temperature of the gas). As a consequence of perfectly obeying the ideal gas law, a perfect gas also obeys Boyle’s law and Charles’ law. It is important to note that no known gas holds the properties of a perfect gas. An accurate description of the behaviour of a real gas is provided by the general gas law (when the absolute temperature is sufficiently high and the pressure is sufficiently low). A perfect gas must also obey Avogadro’s law, which provides a relationship between the volume occupied by the gas and the amount of gaseous substance (total number of moles of gas).