Physical Principles and Methods of Single-Molecule Spectroscopy in Solids; Excitation and Emission Spectroscopy and Quantum Optical Measurements; Polarization and Lifetime Measurements, External Pertubations and Microscopy; Spectral Jumps of Single Molecules; Theoretical Models for the Spectral Dynamics of Individual Molecules in Solids; Magnetic Resonance of Single Molecular Spins; Near -Field Optical Imaging and Spectroscopy of Single Molecules; Single-Molecules Detection in Analytical Chemistry.