This document discusses analog properties and z-transforms. It begins with introducing analog and digital signals, and the applications of analog signals. Then it classifies systems as continuous/discrete, time-invariant/time-varying, causal/non-causal, stable/unstable, and linear/nonlinear. Several examples of different system types are provided. The document goes on to explain z-transforms, the z-plane, region of convergence, z-transform pairs, and applications of z-transforms including signal processing and solving differential equations.