The channel processes are seen as complex phenomena related to channel - bed interaction, erosion, transport of sediments and alluviation, the notion is used as a basis for channel processes typization. The types of channel processes are shown to correspond to channels' subdivision into those of plain, semi-mountain, and mountain rivers. That forms the first block of the morphodynamic classification of river channels which includes also morphological types of channels (with wide floodplain, incised, adapted ones), types of bed macroforms, morphodynamic types of channels, bedford hierarchy, and types of channel landforms, each group forming an individual block in classification. Morphodynamic channel types are considered with reference to plain rivers. Unresolved problems of the river channel classification are pointed out.