  The use of emulsions as particles detector has a long and successful life.
The recent development of fast automatized analysis systems has allowed the use
of huge amount of emulsions films with no precedence in the history of particle
physics. The OPERA experiment, running in the underground Laboratori Nazionali
del Gran Sasso (LNGS), for the confirmation of the neutrino oscillation in the
$\nu_{\mu}\to\nu_{tau}$ channel, is "the major" of these experiments. The
experimental technique, the strategy and the first results of the experiment
are presented.
