This memoir is a presentation of the works carried out by the author in ring and module theory. More precisely the author studied arithmetical commutative rings, in particular valuation rings (which are not necessarily integral domain). The most remarkable result is the proof of the following fact: any local ring of bounded module type is an almost maximal valuation ring. Are also presented some results on the localization of injective modules and on the pure-injective hulls of some classes of modules.
