Any system that changes over time. Change can be continuous or discontinuous, and there are mathematical tools available (e.g., catastrophe theory) for distinguishing between these two types of change (and whether discontinuous changes are quantitative or qualitative in nature). The dynamics involved do not necessarily refer only to mechanical forces and masses as in Newtonian mechanics, but also to the most simple and abstract description of how the global behavior of a system evolves over time. Based on this distinction, there are two general classes of dynamical systems: linear and non-linear. More mathematically, when the temporal evolution of a system can be predicted based on its current state, then the system is a dynamical system. It can be characterized by a differential equation (or an iterative map if time is measured in discrete units). The mathematical theory of dynamical systems emphasizes qualitative properties of the solutions of such equations (e.g., their convergence in time to attractor states and their sensitivity to small changes of the equation).
See Attractors, Bifurcation, Catastrophe theory, Control parameter, Differential equation, Dynamical balance, Dynamical coupling, Dynamical parameters, Dynamical systems approaches, Linear dynamical systems, Movement, Newtonian (or classical) mechanics, Non-linear dynamical systems, Numbers, Order parameter, System