ELEC 221 is an introduction to the mathematical description and modelling of signals and systems. The term signals refers to means to convey information (e.g., sound, image, money deposits), and systems refer to processes generating and transforming signals (e.g., loudspeaker, camera, bank account). Central concepts that will be covered concern: the description of signals and systems through functions, the composition of complex systems from simpler subsystems, the notion of states and finite state machines, discrete-time and continuous-time systems, frequency domain descriptions and analyses of signals and systems.