The theory of solitons in crystallographically ordered charge density waves (CDW) at low temperatures is developed. Various types of solitons, which appear in a course of electron's self-trapping, are described. The adaptation of CDW media to the formation of π- and π- solitons is considered. A model independent approach is suggested to describe interactions of solitons with the Coulomb field and with phase deformations of CDW. The effects of screening, self-screening and commensurability are considered. Interactions between solitons and with impurities are described. Cases of attraction among solitons are found, which may lead to their aggregation into microscopical centers.