Possible domain structure in p-wave superconductors with
broken time-reversal symmetry is intensively discussed in
literature in connection with failed experimental attempts
to detect stray magnetic fields in Sr2RuO4, which were
theoretical predicted for these materials. This puts in
question the  very idea of p-wave pairing. The lecture
starts from the short overview of the domain-structure
concept in normal ferromagnets, then switches to domains in
systems with coexistence of ferromagnetism and
superconductivity (superconducting ferromagnets), and
finally addresses  domain structure and stray magnetic
fields in p-wave superconductors, in which ferromagnetism
originates from the electron orbital moment but not from spin.