  We give a self-contained introduction to the theory of Turaev's shadows as a
tool to study 3 and 4-manifolds. The goal of the present paper twofold: on one
side it is intended to be a shortcut to a basic use of the theory of shadows,
on the other side it gives a sketchy overview of some of the recent results on
shadows. No original result is proved here and most of the details of the
proofs are not included.
