This book presents a coherent framework for understanding the dynamics of piecewise-smooth and hybrid systems. An informal introduction motivates the ubiquity of such models via examples from mechanics, electronics, control theory and physiology. The key concept is that of discontinuity-induced bifurcation, which generalizes diverse phenomena such as grazing, border-collision, sliding, chattering and the period-adding route to chaos. The results are presented in an informal style, illustrated via many examples, both theoretical and experimental. The book is aimed at a wide audience of applied mathematicians, engineers and scientists at the beginning postgraduate level. Almost no mathematical background is assumed other than basic calculus and algebra.