"Signals and Systems" is intended as a textbook and workbook for students of information technology, communications engineering, computer science, and related fields. Since it develops the curriculum through practical tasks with detailed solutions, it is also suitable for engineers and computer scientists for self-study in their professional practice. The fundamentals are presented in a compact form. By contrasting continuous-time and discrete-time signals and systems, the common concept is clearly emphasized, allowing for a synergy in learning. Due to the compilation of important formulas in tables and the many solved problems, it also serves as a reference work. The rapid development of information technology has led to a shift in focus in the applications of signal and system theory: from the classical theory of filters, networks, and lines to complex algorithms of digital signal processing. This book addresses this development by treating classical methods succinctly while giving more space to digital signal processing and stochastic signals in information technology.