The article presents a review of the current state of the theory of avalanche-streamer processes, i.e., processes occurring during the development of discharges in dense gases. The principal attention is devoted to description of the physical picture of the phenomena. A systematic presentation is given of the theory of the main stages of formation of a discharge: the theory of electron avalanches, the theory of a selfmaintaining discharge, the theory of the avalanche-streamer transition, and the theory of streamers. The question of breakdown of long spark gaps is discussed briefly.

@article{Lozanskii:1975,
	author = {É. D. Lozanskii},
	title = {Development of electron avalances and streamers},
	publisher = {Physics-Uspekhi},
	year = {1975},
	journal = {Phys. Usp.},
	volume = {18},
	number = {11},
	pages = {893-908},
	url = {https://ufn.ru/en/articles/1975/11/c/},
	doi = {10.1070/PU1975v018n11ABEH005235}
}