Theoretical and experimental investigations of charged dislocations in alkali halide crystals are reviewed. A description is given of the fine structure of an edge dislocation with defects on the dislocation line. A systematic account is given of theories of a sessile charged dislocation ranging from its representation by an infinitely long charged filament to an allowance for the fine structure of the dislocation line. Phenomenological models dealing with a charge on a moving dislocation are discussed. Forces acting on a dislocation are considered and the characteristics of its motion under the influence of an external mechanical load and of an electric field are dealt with. The direct and converse dislocation piezoelectric effects are described for a crystal containing mobile charged dislocations. In presentation of experimental results special attention is given to studies providing quantitative estimates of the linear charge density on a dislocation.