The paper is organized as follows. After introducing the physical system we consider briefly the pendulum’s behaviour in the case of rapid oscillations of the pivot including dynamical stabilization of the inverted pendulum, which is important for understanding the origin of subharmonic resonances (“multiple-nodding” oscillations). Then we investigate the spectral composition of subharmonic resonances in the low-amplitude limit and determine the boundaries of the region in the parameter space in which these resonances can exist. Next we consider the destabilization of the dynamically stabilized pendulum (the “flutter” mode) and its relationship with ordinary parametric resonance. Then the influence of friction is taken into account. We report also for the first time about several new types of regular behaviour of the parametrically driven pendulum discovered with the help of computer simulations.