Fractal clusters, i.e., systems formed as a result of the aggregation of solid particles executing Brownian motion in space, are discussed. Studies of fractal clusters and of the dynamics of their formation, based on modern computational techniques, are reviewed. Experimental studies of fractal clusters, and processes and phenomena in which they manifest themselves, are examined. An analysis is given of a model of ball lightning in which the active material has the structure of a fractal cluster.

@article{Smirnov:1986,
	author = {B. M. Smirnov},
	title = {Fractal clusters},
	publisher = {Physics-Uspekhi},
	year = {1986},
	journal = {Phys. Usp.},
	volume = {29},
	number = {6},
	pages = {481-505},
	url = {https://ufn.ru/en/articles/1986/6/a/},
	doi = {10.1070/PU1986v029n06ABEH003414}
}