In Chap. 13 angular momentum transport by magnetic fields was examined. The rotation of the Sun is really believed to be decelerated by magnetic torque due to the magnetized solar wind to its present angular momentum. Similar processes may govern the contraction of protostellar gas clouds. In accretion disks, angular momentum transport from their inner part to outer part is usually done by magnetic turbulent viscosity. Furthermore, in the case of binary systems the angular momentum of stellar rotations will be extracted to orbital motions. In the case of a single black hole system, the angular momentum extraction from disks by magnetic fields will be of important. In such systems angular momentum may be eventually carried off in a jet moving perpendicular to the disk. Considering such situations, we present the essence of the solar MHD winds, and algebraic relations describing physical and dynamical quantities in steady axisymmetric MHD flows, as important bases for studying MHD flows in various astrophysical objects.