Gas breakdown, steady-state maintenance and the continuous generation of a low-temperature plasma, and propagation of the plasma fronts, all are induced by laser radiation. By nature, and in conformity with the fundamental laws, these effects are not different from similar processes that occur in constant and alternating fields and which are a traditional subject of the study of the physics of gas discharge. In fact, a new chapter has been added to the gas-discharge sciences: discharge at optical frequencies. It is a rapidly developing new field which encourages both new experiments and applications. It appears useful at this time to characterize the position occupied by the new field within the general framework of discharge sciences, and to analyze and appraise the latest results.