This comprehensive textbook emphasizes the difference between models and the physical signals and systems they represent. Beginning with continuous-time topics and progressing to discrete-time materials, yet flexible for courses that treat them in parallel, Signals, Systems, and Transforms: introduces signals and systems and describes several physical continuous-time and discrete-time systems; covers the Fourier series, the Fourier transform for continuous-time signals and systems, the Laplace transform, and state variables for continuous-time systems; develops the z-transform with the discrete-time Fourier transform and the discrete Fourier transform, and gives state variables for discrete-time systems. In addition, the authors integrate the software tool MATLAB as much as possible in examples and homework problems.