1. Introduction.- 2. The Thermodynamics of Photoferroelectrics.- 2.1 The Free Energy of a Ferroelectric Semiconductor.- 2.2 First- and Second-Order Phase Transitions.- 2.3 Effect of Electrons on Phase Transitions: Photoferroelectric Phenomena.- 2.4 The Energy-Gap Anomaly.- 2.5 Electrical Conductivity of Ferroelectric Semiconductors Near the Curie Point.- 3. The Microscopic Theory of Photoferroelectric Phenomena.- 3.1 Ferroelectric Phase Transitions and the Soft Vibration Mode..- 3.2 Effect of Screening on the Soft Vibration Mode.- 3.3 Ferroelectric Phase Transitions and Interband Electron-Phonon Interactions.- 3.4 Change in Dipole Moment of Centres on Optical Recharging.- 3.5 Phasons and Fluctuons.- 4. Screening of Spontaneous Polarization.- 4.1 Debye Length as Screening Length Parameter in Ferroelectrics.- 4.2 Screening and Periodic Structure of Interphase Boundaries in Ferroelectrics.- 5. Photoferroelectric Phenomena and Photostimulated Phase Transitions.- 5.1 Thermodynamics of Photoferroelectric Phenomena.- 5.2 Photostimulated Shift of Phase Transition Temperature and Photohysteresis Effect.- 5.3 Influence of Electron Excitations on Spontaneous Polarization.- 5.4 Photodeformation Effect.- 5.5 Photoinduced Rayleigh Scattering in BaTiO3.- 6. The Anomalous Photovoltaic Effect in Ferroelectrics.- 6.1 The APV Effect in Ferroelectrics.- 6.2 Photovoltaic Current with Short-Circuited Electrodes.- 6.3 The Nature of the AP Effect in Ferroelectrics.- 6.3.1 Asymmetry of Impurity Centers and Frank-Condon Relaxation.- 6.3.2 Photoinduced Fluctuations.- 7. The Photorefractive Effect in Ferroelectrics.- 7.1. Mechanisms of the PR Effect in Ferroelectrics.- 7.1.1 The AP Effect.- 7.1.2 The Influence of Electron Excitations on Spontaneous Polarization.- 7.1.3 The Diffusion of Nonequilibrium Carriers.- 7.1.4 The Photoconductivity in an External Field.- 7.2. Photorefractive Holographic Recording.- 7.3 Photorefractive Sensitivity.- 7.4 Effect of Photorefraction on Multiphoton Excitation.- 8. Screening Phenomena.- 8.1 Influence of Nonequilibrium Carriers on Screening of Interfaces.- 8.2 Influence of Screening on Switching Processes.- 8.2.1 Photoswitching in SbSI.- 8.2.2 Photoswitching in PLZT.- 8.3 The Photodomain Effect.- 8.3.1 The Photodomain Effect in SbSI and BaTiO3.- 8.3.2 The Influence of Intrinsic Illumination on Pyrocurrents in SbSI and BaTiO3.- 8.4 Screening and Short-Circuit Photocurrents.- References.