  Possible effects of large-scale magnetic fields on the Cosmic Microwave
Background (CMB) are reviewed. Depending on the specific branch of the spectrum
of plasma excitations, magnetic fields are treated either within a two-fluid
plasma description or within an effective (one-fluid) approach. The uniform
field approximation is contrasted with the fully inhomogeneous field
approximation. It is argued that the interplay between CMB physics and
large-scale magnetic fields will represent a rather interesting
cross-disciplinary arena along the next few years.
