This book analyzes for the first time the rotational motion of different quantum systems from a common perspective. Starting from the well known rotor of classical mechanics, it discusses the properties of rotating molecules, nuclei, and hadrons from a common perspective. Rotation in non-spatial degrees of freedom, associated with pair condensates of fermionic systems is also considered. It introduces new elements that emerge on the different length and energy scales of the different systems and points out familiar concepts that must be given up. It analyzes thoroughly how the sequences of rotational quantum states (bands) emerge from the spontaneous breaking of rotational symmetry by the mean field. Combining the rotating mean field (Cranking Model) with semi-classical quantization provides the basis for calculating the rotational bands in the various systems. Much care is devoted to the relation between the discrete symmetries of the rotating mean field and the spin, parity, and multiplicity of the quantal states comprising a rotational band. This new perspective demonstrates how similar rotational structures emerge in various systems the constituents of which organize in a radically different way.The book focuses on nuclear rotation, the concepts of which had to be substantially extended during the last two decades in order to account for the new experimental results on rapidly rotating nuclei, where the angular frequency becomes comparable with characteristic frequencies of the nucleonic motion. This high-spin regime differs dramatically from the adiabatic regime of molecules, where the electronic motion is much faster than the rotational motion of the nuclei. The concept of the rotating mean field turned out to be the adequate theoretical approach. This important work discusses the rotation of nuclei and non-nuclear quantal systems from this unifying perspective.