  The mechanism of classical novae explosions is explained, together with some
of their observational properties. The scarce but not null impact of novae in
the chemical evolution of the Milky Way is analyzed, as well as their relevance
for the radioactivity in the Galaxy. A special emphasis is given to the
predicted gamma-ray emission from novae and its relationship with the
thermonuclear model itself and its related nucleosynthesis.
