A review is given of the current status of the self-induced transparency effect. The McCall--Hahn theory (2$\pi$ pulses) is considered and its generalization to the case of phase modulation of radiation pulses, degeneracy of transitions, and two-photon resonance is discussed. The relationship with the theory of nonlinear waves, obeying the Korteweg--de Vries equation, is pointed out. The possibility of similar coherent effects in direct interband transitions in semiconductors is discussed. A summary is given of the experimental results demonstrating a strong fall in the absorption and a considerable slowing down of light pulses, typical of the self-induced transparency. Possible physical applications of the effect, based on these properties, are discussed.

@article{Poluektov:1975,
	author = {I. A. Poluektov and Yu. M. Popov and V. S. Roitberg},
	title = {Self-induced transparency effect},
	publisher = {Physics-Uspekhi},
	year = {1975},
	journal = {Phys. Usp.},
	volume = {18},
	number = {5},
	pages = {673-690},
	url = {https://ufn.ru/en/articles/1975/5/l/},
	doi = {10.1070/PU1975v017n05ABEH004365}
}