Data on interstellar diffractive and refractive scintillation of pulsars are analyzed. The comparison between the theory and the observational data shows that two types of spectra for electron density fluctuations are realized in the interstellar medium: simple power law and piecewise with a break. The distribution of turbulent plasma in the Galaxy has a two component structure. Component A is diffuse and it is distributed outside of the spiral arms of the Galaxy. Component B is cloudy and it is associated with Galactic arms. The origin of the interstellar plasma turbulence is considered. The possible sources of turbulent energy are discussed. The contribution of supernova bursts in the interstellar gas ionization and generation of turbulence are analyzed among other factors.