  About 120 baryons and baryon resonances are known, from the abundant nucleon
with $u$ and $d$ light-quark constituents up to the recently discovered
$\Omega_b^-=bss$, and the $\Xi_b^-=bsd$ which contains one quark of each
generation. In spite of this impressively large number of states, the
underlying mechanisms leading to the excitation spectrum are not yet
understood. Heavy-quark baryons suffer from a lack of known spin-parities. In
the light-quark sector, quark-model calculations have met with considerable
success in explaining the low-mass excitations spectrum but some important
aspects like the mass degeneracy of positive-parity and negative-parity baryon
excitations are not yet satisfactorily understood. At high masses, above 1.8
GeV, quark models predict a very high density of resonances per mass interval
which is not observed. In this review, issues are identified discriminating
between different views of the resonance spectrum; prospects are discussed how
open questions in baryon spectroscopy may find answers from photo- and
electro-production experiments which are presently carried out in various
laboratories.
