The first type of complementarity considered is purely mathematical. It has to do with the Fourier transform of scalar functions of several variables and presents inequalities concerning "dispersions' of associated variables of the original function and its transform.The following types deal with inequalities concerning quantum physics (Heisenberg) on one side and macrophysics on the other. An "informational" presentation is proposed.The last kind of complementarity has to do with duality in dynamical systems where only the probability densities of the initial states of the two dual systems are known. The probability densities of the states vary with time but the sum of associated "informations' remains invariant. Conclusion considers complementarities as aspects of a higher level unity to be discovered or as a by-product of an artificial decomposition.