The law that relates pressure and volume of gases is known as Boyle's Law. This fundamental principle states that the pressure of a gas is inversely proportional to its volume when the temperature remains constant. In mathematical terms, this can be expressed as \(PV = k\), where \(P\) is pressure, \(V\) is volume, and \(k\) is a constant. This relationship helps explain various physical phenomena, such as how gas behaves when compressed or allowed to expand, which is vital in fields like thermodynamics and engineering.