1. Introduction.- 1.1 Structure of Point Defects.- 1.2 Basic Concepts of Defect Structure Determination by EPR.- 1.3 Superhyperfine and Electronic Structures of Defects in Solids.- 2. Fundamentals of Electron Paramagnetic Resonance.- 2.1 Magnetic Properties of Electrons and Nuclei.- 2.2 Electrons and Nuclei in an External Magnetic Field.- 2.3 Some Useful Relations for Angular Momentum Operators.- 2.4 Time Dependence of Angular Momentum Operators and Macroscopic Magnetization.- 2.5 Basic Magnetic Resonance Experiment.- 2.6 Spin-Lattice Relaxation.- 2.7 Rate Equations for a Two-Level System.- 2.8 Bloch Equations.- 2.9 Conventional Detection of Electron Paramagnetic Resonance and its Sensitivity.- 3. Electron Paramagnetic Resonance Spectra.- 3.1 Spin Hamiltonian.- 3.2 Electron Zeeman Interaction.- 3.3 g-Factor Splitting of EPR Spectra.- 3.4 Fine-Structure Splitting of EPR Spectra.- 3.5 Hyperfine Splitting of EPR Spectra.- 3.6 Superhyperfine Splitting of EPR Spectra.- 3.7 Inhomogeneous Line Widths of EPR Lines.- 4. Optical Detection of Electron Paramagnetic Resonance.- 4.1 Optical Transitions of Defects in Solids.- 4.2 Spectral Form of Optical Transitions of Defects in Solids.- 4.3 EPR Detected with Magnetic Circular Dichroism of Absorption Method.- 4.4 MCDA Excitation Spectra of ODEPR Lines (MCDA “Tagged” by EPR).- 4.5 Spatially Resolved MCDA and ODEPR Spectra.- 4.6 Measurement of Spin-Lattice Relaxation Time T1with MCDA Method.- 4.7 Determination of Spin State with MCDA Method.- 4.8 EPR of Ground and Excited States Detected with Optical Pumping.- 4.9 EPR Optically Detected in Donor-Acceptor Pair Recombination Luminescence.- 4.10 Optically Detected EPR of Triplet States.- 4.11 ODEPR of Trapped Excitons with MCDA Method.- 4.12 Sensitivity of ODEPR Measurements.- 4.13 Structural Information from Forbidden Transitions in MCDA-EPR Spectra.- 4.14 Spatial Correlation Between Defects by Cross-Relaxation-Spectroscopy.- 4.15 High-Field ODEPR/ODENDOR.- 5. Electron Nuclear Double Resonance.- 5.1 The Resolution Problem, a Simple Model.- 5.2 Type of Information from EPR and NMR Spectra.- 5.3 Indirect Detection of NMR, Double Resonance.- 5.4 Examples of ENDOR Spectra.- 5.5 Relations Between EPR and ENDOR Spectra, ENDOR-Induced EPR.- 5.6 Electron Nuclear Nuclear Triple Resonance (Double ENDOR).- 5.7 Temperature Dependence and Photo-Excitation of ENDOR Spectra.- 5.7.1 Temperature Dependence of ENDOR Spectra.- 5.7.2 Photo-Excitation of ENDOR Spectra.- 5.8 Stochastic ENDOR.- 6. Analysis of ENDOR Spectra.- 6.1 Qualitative Analysis of ENDOR Spectra.- 6.1.1 Spin Hamiltonian.- 6.1.2 Simple First Order Solution.- 6.1.3 Assignment of Nuclei.- 6.1.4 Angular Dependence of ENDOR Lines.- 6.1.5 Symmetry Considerations, Neighbor Shells.- 6.2 Quantitative Analysis of ENDOR Spectra.- 6.2.1 Higher Order Approximations.- 6.2.2 Large Anisotropic Hyperfine Interactions.- 6.2.3 Approximation with the Effective Electron Spin Seff.- 6.2.4 Second Order Splittings of the Superhyperfine Structure.- 6.2.5 Sample Alignment.- 6.2.6 Reconstruction of the EPR Line Shape from ENDOR Data.- 6.2.7 Asymmetric Superhyperfine Tensors.- 6.2.8 Selection Rules and ENDOR Line Intensities.- 6.2.9 ENDOR Spectra in the Case of a Large Quadrupole Interaction and Axial Symmetry.- 6.2.10 Powder ENDOR Spectra.- 6.2.11 Final Results Obtainable from the Analysis of ENDOR Spectra.- 7. Electrical Detection of Electron Paramagnetic Resonance.- 7.1 Experimental Methods to Detect EDEPR.- 7.2 Experimental Observation of EDEPR.- 7.3 The Donor-Acceptor Pair Recombination Model.- 7.4 On the Role of the Electron Irradiation for the Donor EPR in Silicon.- 7.5 Spatial Resolution and Low Frequency EDEPR.- 7.6 Electrical Detection of ENDOR.- 7.7 Concentration and Temperature Dependence of the EDEPR Signals.- 7.8 Further Spin-Dependent Recombination Models.- 7.8.1 The Lépine Model.- 7.8.2 The Model of Kaplan, Solomon and Mott.- 7.8.3 The Spin-Dependent SRH Model.- 8. Theoretical ab initio Calculations of Hyperfine Interactions.- 8.1 Electron States in Solids.- 8.1.1 Born-Oppenheimer Approximation.- 8.1.2 Hartree and Hartree-Fock Approximations.- 8.1.3 Density Functional Theory and Local Density Approximation.- 8.1.4 Computational Methods for Energy Band Calculations.- 8.2 Computational Methods for Deep Point Defects.- 8.2.1 Cluster Methods.- 8.2.2 The Supercell Method.- 8.2.3 Green’s Function Methods.- 8.2.4 The Band Gap Problem and the Scissor Operator.- 8.3 Hyperfine Interactions.- 8.3.1 Non-relativistic Hyperfine Interactions.- 8.3.2 Scalar Relativistic Hyperfine Interactions.- 8.3.3 Magnetization Density for Many-Electron States.- 8.3.4 The Jahn-Teller Effect.- 8.3.5 The Core Polarization.- 8.3.6 Electrical Quadrupole Interaction.- 8.3.7 The Empirical LCAO Scheme.- 8.3.8 The Envelope Function Method.- 8.3.9 Point Dipole-Dipole Interaction.- 8.4 Deep Point Defects in Semiconductors and Insulators.- 8.4.1 Substitutional Donors with ?z = 1.- 8.4.2 Substitutional Donors with ?z = 2.- 8.4.3 Interstitial Deep Donors.- 8.4.4 Shallow Acceptors with ?z = -1.- 8.4.5 Deep Acceptors with ?z = -2.- 8.4.6 Vacancies.- 8.4.7 Point Defects in Ionic Solids.- 8.4.8 3d Transition Metal Defects.- 8.4.9 Interstitial 3d TM Defects.- 8.5 Shallow Defects: The Effective Mass Approximation and Beyond.- 8.5.1 The EMA Formalism.- 8.5.2 Simplest Case: Nondegenerate Band Edge.- 8.5.3 Conduction Band with Several Equivalent Minima.- 8.5.4 Pseudopotential Calculations.- 8.5.5 Degenerate Valence Bands.- 8.6 Conclusions.- 9. Experimental Aspects of Optically Detected EPR and ENDOR.- 9.1 Sensitivity Considerations.- 9.1.1 Magnetic Circular Dichroism of Absorption.- 9.1.2 Optically Detected EPR.- 9.2 ODMR Spectrometers Monitoring Light Emission.- 9.3 ODMR Spectrometers Monitoring Magnetic Circular Properties of Absorption and Emission.- 9.3.1 General Description of the Spectrometer.- 9.3.2 Measurement of Magnetic Circular Dichroism of Absorption.- 9.3.3 Measurement of Magnetic Circular Polarization of Emission.- 9.4 Experimental Details of the Components of an MCDA/MCPE ODMR Spectrometer.- 9.4.1 Light Sources.- 9.4.2 Monochromators.- 9.4.3 Imaging Systems.- 9.4.4 Linear Polarizers.- 9.4.5 Photo-Elastic Modulator.- 9.4.6 Detectors.- 9.4.7 Cryostat.- 9.4.8 Magnet.- 9.4.9 Microwave System and Cavity.- 9.4.10 Radio-Frequency System for ODENDOR.- 9.4.11 Control and Registration Electronics.- 9.5 High Frequency ODEPR/ODENDOR Cavities.- 9.5.1 Cylindrical V-Band Cavity.- 9.5.2 Cylindrical Cavity for W-Band MCDA-EPR/ENDOR.- 9.5.3 Multimode W-Band Fabry-Pérot Cavity for MCDA-EPR/ENDOR.- 9.6 High Pressure Photoluminescence-Detected EPR.- Appendices.- References.