The book presents the core theory of control engineering, together with its foundations in signals and systems. These foundations include continuous-time systems using the Laplace transform, discrete-time systems using the z-transform, and sampled-data systems connecting the two domains. The classical theory of control covers the analysis of the dynamic response of linear time-invariant systems, root-locus techniques for feedback design, and the frequency-domain analysis of closed-loop systems. Control engineering is strongly related to signal processing and communications, and the book includes a discussion of phase-locked loops as an example of feedback control. To the extent possible, the origin of the theoretical results is explained, and the technical details needed to reach a more complete understanding of the concepts are included. On the other hand, the book does not present design studies or specialized topics, for which the reader is referred to the bibliography. Material complementing the book is available through the author's web page, including solutions to selected problems and virtual lab experiments.