A complete mathematical solution exists for the distillation of ideal multicomponent mixtures, i.e., mixtures with constant relative volatilities, allowing to answer all questions arising in the distillation of such mixtures by relatively simple algebraic equations. As shown in this paper, the distillation of a real mixture of any complexity may - at least qualitatively - be reduced to the distillation of an ideal mixture. The understanding of the distillation behavior of complex real mixtures is thus greatly simplified and useful both in the design as well as the operation of multicomponent distillation columns.