  This contribution reviews recent advances in the possible identification of
blazars as potential sources of at least some of the very-high-energy neutrinos
detected by the IceCube neutrino detector at the South Pole. The basic physical
requirements for neutrino production and physics constraints that may be drawn
from neutrino - blazar associations are reviewed. Several individual cases of
possible associations will be discussed in more detail. It is emphasized that
due to $\gamma\gamma$ opacity constraints in efficiently neutrino-producing
blazars, an association between X-ray -- soft $\gamma$-ray activity and
very-high-energy neutrino production is more naturally expected than a
connection between neutrino and high-energy/very-high-energy $\gamma$-ray
activity.
