The book contains the only available complete presentation of the mode-coupling theory (MCT) of complex dynamics of glass-forming liquids, dense polymer melts, and colloidal suspensions. It describes in a self-contained manner the derivation of the MCT equations of motion and explains that the latter define a model for a statistical description of non-linear dynamics. It is shown that the equations of motion exhibit bifurcation singularities, which imply the evolution of dynamical scenarios different from those studied in other non-linear dynamics theories. The essence of the scenarios is explained by the asymptotic solution theory of the equations of motion. The leading-order results deal with scaling laws and the range of validity of these general laws is obtained by the derivation of the leading-correction results. Comparisons of numerical solutions of the MCT equations of motion with the analytic results of the asymptotic analysis demonstrate various facets of the MCT dynamics. Some comparisons of MCT results with data are used to show the relevance of MCT for the discussion of amorphous matter dynamics.