At the end of the nineteenth century Lyapunov and Poincaré developed the
so called qualitative theory of differential equations and introduced
geometric- topological considerations which have led to the concept of
dynamical systems. In its present abstract form this concept goes back
to G.D. Birkhoff. This is also the starting point of Chapter 1 of this
book in which uncontrolled and controlled time-continuous and
time-discrete systems are investigated. Controlled dynamical systems
could be considered as dynamical systems in the strong sense, if the
controls were incorporated into the state space. We, however, adapt the
conventional treatment of controlled systems as in control theory. We
are mainly interested in the question of controllability of dynamical
systems into equilibrium states. In the non-autonomous time-discrete
case we also consider the problem of stabilization. We conclude with
chaotic behavior of autonomous time discrete systems and actual
real-world applications.