This chapter is devoted to high-frequency magnetic processes in such ‘unsaturated’ (i.e., split into domains) ferromagnetic samples. In thin films with easy axes of magnetization lying in the plane of the film, Bloch walls do not correspond to the minimum of total energy because of the demagnetizing fields and, hence, of the magnetic energy arising due to the magnetization components normal to the film surface. Then, the Neel walls appear, in which the magnetization lies in the plane perpendicular to the domain boundary and parallel to the film surface. If the frequency of the ac magnetic field is much less than all the characteristic frequencies of a ferromagnetic sample, the change of its magnetization is occurring quasistatically. This means that the magnetic state at a certain moment is determined by the value of the ac magnetic field at the same moment.