  We review the main ingredients for an unconventional pairing state in the
ferropnictides, with particular emphasis on interband pairing due to magnetic
fluctuations. Summarizing the key experimental prerequisites for such pairing,
the electronic structure and nature of magnetic excitations, we discuss the
properties of the s+/- state that emerges as a likely candidate pairing state
for these materials and survey experimental evidence in favor of and against
this novel state of matter.
