The monograph is devoted to the physics of micropixel avalanche photodiodes (MLPD), also called silicon photomultiplier tubes (Si-PMT). The stages of development and physical mechanisms of the most promising designs of such devices are briefly considered. Methods for improving the amplitude and timing of MDF are discussed, as well as the possibility of creating other avalanche devices, such as avalanche single-photon CCD arrays and avalanche amplifiers of electrical signals. The book is intended for specialists involved in the development, research and application of semiconductor detectors.