Since their introduction in the late eighties and early nineties of the last century, flat systems have become well established in control theory and also in control engineering. This stems from the fact that for this class of systems trajectories can be planned easily. Moreover, for lumped parameter systems these trajectories can be stabilized in a straightforward way. In this contribution, after a short introduction the basics of control design, trajectory planning and stabilization are shown. These are then demonstrated by two simple examples, namely a gyroscopic pendulum as well as a uniaxial model of a car. As more extensive illustrative example finally trajectory planning and nonlinear control for a gantry crane are discussed, where theoretic results, simulations and laboratory experiments are presented.