Preface -- Quantum Ring: A Unique Playground for the Quantum-Mechanical Paradigm -- Fabrication, Characterization and Physical Properties -- Growth and Spectroscopy of Semiconductor Quantum Rings -- Quantum Rings: Fabrication and Optical Properties -- Self-organized Quantum Rings: Physical Characterization and Theoretical Modeling -- Scanning-probe Electronic Imaging of Lithographically Patterned Quantum Rings -- Self-organized Formation and XSTM-Characterization of GaSb/GaAs Quantum Rings -- Self-assembled Semiconductor Quantum Rings Complexes by Droplet Epitaxy: Growth and Physical Properties -- Aharonov-Bohm Effect for Excitons -- New Versions of the Aharonov-Bohm Effect in Quantum Rings -- Aharonov-Bohm Effect for Neutral Exctions in Quantum Rings -- Optical Aharonov-Bohm Effect in Type-II Quantum Dots -- Theory -- Strained Quantum Rings -- Theoretical Modeling of Electronic and Optical Properties of Semiconductor Quantum Rings -- Coulomb Interaction in Finite-Width Quantum Rings. Differential Geometry Applied to Rings and Möbius Nanostructures -- Hole Mixing in Semiconductor Quantum Rings -- Engineering of Electron States and Spin Relaxation in Quantum Rings and Quantum Dot-Ring Nanostructures.