Signals and Systems by Nahvi is intended for use in a signals and systems course at the undergraduate junior level. The book covers the analysis of signals and linear systems in the time and frequency domains and is organized into 18 chapters. The chapters are modular with sections and there are no sub-sections. The modular structure of the chapters provides a quick and direct approach to each topic within the chapters and makes the book a convenient tool for instructional needs in a wide range of teaching scenarios and at various levels of complexity. Continuous-time and discrete-time domains are treated separately in two parts. This allows the book to be used for instructions on either domain separately. It may also be used for courses teaching the two domains simultaneously, as the chapters in part one and two provide parallel presentations of each subject.