Аннотация:A classification of solar wind streams according to the main hydrodynamic parameters — a combination of the velocity (fast or slow), temperature (hot or cold) and density (dense or rarefied) of protons — is considered. According to this approach, we specify eight types of the solar wind: fast-hot-dense (FHD), fast-hot-rarefied (FHR), fast-cold-dense (FCD), etc. As an additional parameter, the proton plasma beta is taken into account for description of the magnetic state of solar wind streams (high-, mid-, low-magnetized subtypes). The listed types of streams occur with different frequencies depending on the phases of solar activity cycles. This classification is compared with the classical division of solar wind streams into high-speed streams (HSSs) from coronal holes, coronal mass ejections (CMEs) and slow solar wind from the streamer belt. The comparison is carried out for the events in August 2010 and May 2011 when CME–CME and CME–HSS interactions, respectively, were observed. In both cases there was the rare FCD-type of the wind. We concluded that the classical description of the large-scale structure of solar wind (hours and days), in particular, consideration of the solar wind ion composition, makes it possible to determine the nature and source of solar wind streams, whereas consideration of the hydrodynamic parameters including beta is useful for a detailed description of the small-scale structure (minutes) of complex regions appeared in the cases of interaction of several streams in the heliosphere.