Progress in our knowledge of the fundamental constants of physics

The measurements of quantities providing information on the values of the fundamental physical constants bring together a wide variety of measurements in very different parts of physics in a unique way. Taken both separately and together these measurements provide stringent tests of theory. They also throw light on the question: `How well do we understand physics via measurements at the highest level of accuracy?' They also have important practical applications. In this way they can point the way to the inadequacies and strengths of our knowledge and be used to benefit mankind.