This book covers nonequilibrium statistical physics. Part one, aimed at undergraduates, introduces Langevin equations, general stochastic processes, kinetic theory, fluctuation theory, linear response theory, and stochastic thermodynamics. Part two discusses advanced topics and how to build nonequilibrium stochastic models. Applications, including climate systems, information theory, granular and active matter, and non-intuitive phenomena like negative mobility, are explored in the final three chapters.