The Static and Dynamic Invariants that Characterize Chaos and the Relations Between Them in Theory and Experiments

A short review of the theory and experimental measurement of the static and dynamical invariants that characterize chaotic motions is presented. There is an infinity of such quantities which remain invariant under a smooth change of coordinates, but only the low order ones are relevant for experimental applications. From the theoretical point of view we stress the many interesting relations which exist between the invariants.