This book - perhaps the only of its kind - gives a comprehensive account of Dynamical Systems in a plain non-technical language which is as rigorous as it can be made at this introductory level. Starting from the first steps of differential equations, on the assumption that readers only have a modest mathematical background, it quickly takes them to nonlinear dynamical systems, linearization theory, limit cycles, Gradient, Lagrangean and Hamiltonian dynamical systems. Apart from a new chapter on Floquet theory, Centre Manifold theorems and Liapunov-Schmidt reduction, this second edition also includes new materials, additional examples, illustrations and applications: almost every chapter has been re-written and enlarged to keep up with rapid advances in this field.