  Neutron scattering studies have provided important information about the
momentum and energy dependence of magnetic excitations in cuprate
superconductors. Of particular interest are the recent indications of a
universal magnetic excitation spectrum in hole-doped cuprates. That starting
point provides motivation for reviewing the antiferromagnetic state of the
parent insulators, and the destruction of the ordered state by hole doping. The
nature of spin correlations in stripe-ordered phases is discussed, followed by
a description of the doping and temperature dependence of magnetic correlations
in superconducting cuprates. After describing the impact on the magnetic
correlations of perturbations such as an applied magnetic field or impurity
substitution, a brief summary of work on electron-doped cuprates is given. The
chapter concludes with a summary of experimental trends and a discussion of
theoretical perspectives.
