Abstract: Turbulence and magnetic fields are ubiquitous in the Universe. Magnetohydrodynamic (MHD) turbulence is important for all branches of astrophysics involving gas dynamics. The developments of turbulence theories bring a paradigm shift in many fields of astronomy. I will start from an introduction of modern theories of MHD turbulence and then show some examples for their general applicability in understanding important physical processes in the interstellar medium (ISM), including the formation of density filaments commonly seen in both the diffuse ISM and dense molecular clouds, and the interstellar scattering of Galactic pulsars.<br>