  We review the properties of BPS, or supersymmetric, magnetic monopoles, with
an emphasis on their low-energy dynamics and their classical and quantum bound
states. After an overview of magnetic monopoles, we discuss the BPS limit and
its relation to supersymmetry. We then discuss the properties and construction
of multimonopole solutions with a single nontrivial Higgs field. The low-energy
dynamics of these monopoles is most easily understood in terms of the moduli
space and its metric. We describe in detail several known examples of these.
This is then extended to cases where the unbroken gauge symmetry include a
non-Abelian factor. We next turn to the generic supersymmetric Yang-Mills (SYM)
case, in which several adjoint Higgs fields are present. Working first at the
classical level, we describe the effects of these additional scalar fields on
the monopole dynamics, and then include the contribution of the fermionic zero
modes to the low-energy dynamics. The resulting low-energy effective theory is
itself supersymmetric. We discuss the quantization of this theory and its
quantum BPS states, which are typically composed of several loosely bound
compact dyonic cores. We close with a discussion of the D-brane realization of
${\cal N}=4$ SYM monopoles and dyons and explain the ADHMN construction of
monopoles from the D-brane point of view.
