Coherence and lasers

Recollections are reported about the attitude of N. G. Basov to the problem of coherence of stimulated transitions at the very beginning of studies devoted the creation of masers and lasers. It is shown that the problem of coherence of stimulated transitions can be solved in a multiparticle system. The role of stimulated transitions in a variety of processes proceeding in the nature is discussed. The contribution of N. G. Basov and his school to the development of quantum electronics and laser physics is briefly discussed.