The preferred operational-calculus tool for analysis and design of discrete-time systems. (It should not be confused with the z transformation.) The role of the z transform with regard to discrete-time system is similar to that of the Laplace transform for continuous systems. In fact, the Laplace transform is a specialized case of the z transform. The z transform is by far the more insightful tool, and the Laplace transform is just the limiting case of the z transform in a practical as well as a conceptual way.