Denis Serre is Professor of Mathematics at Ecole Normale SupA(c)rieure de Lyon and a former member of the Institut Universaire de France. He is a member of numerous editorial boards and the author of "Systems of Conservation Laws" (Cambridge University Press 2000). The present book is a translation of the original French edition, "Les Matrices: ThA(c)orie et Pratique," published by Dunod (2001).