After a brief outline of magnetohydrodynamic theory, this introductory book discusses the macroscopic aspects of MHD turbulence, and covers the small-scale scaling properties. Applications are provided for astrophysical and laboratory systems. Magnetic turbulence is the natural state of most astrophysical systems, such as stellar convection zones, stellar winds or accretion discs. It is also found in laboratory devices, most notably in the reversed field pinch.