This textbook offers students at universities, universities of applied sciences, and vocational academies, as well as in further education, detailed access to a fundamental subject with increasing practical relevance. It conveys the contents of the course "Signals and Systems," as they are mostly offered in relevant technical bachelor courses. Thinking and working in the time and frequency domain is to be internalized as a practically useful method. The Fourier transform serves as a uniform tool for the treatment of periodic and aperiodic, continuous-time and discrete-time processes, as well as for system description. The z-transform is treated in conjunction with the modeling of discrete signal processing in digital systems. The Laplace transform, cosine transform, and discrete Fourier transform are presented in a complementary manner.