  In this tutorial paper we summarize how the star formation (SF) history of a
galactic region can be derived from the colour-magnitude diagram (CMD) of its
resolved stars. The procedures to build synthetic CMDs and to exploit them to
derive the SF histories (SFHs) are described, as well as the corresponding
uncertainties. The SFHs of resolved dwarf galaxies of all morphological types,
obtained from the application of the synthetic CMD method, are reviewed and
discussed. In short: 1) Only early-type galaxies show evidence of long
interruptions in the SF activity; late-type dwarfs present rather continuous,
or gasping, SF regimes; 2) A few early-type dwarfs have experienced only one
episode of SF activity concentrated at the earliest epochs, whilst many others
show extended or recurrent SF activity; 3) No galaxy experiencing now its first
SF episode has been found yet; 4) No frequent evidence of strong SF bursts is
found; 5) There is no significant difference in the SFH of dwarf irregulars and
blue compact dwarfs, except for the current SF rates. Implications of these
results on the galaxy formation scenarios are briefly discussed.

Astrophysics of Galaxies;Cosmology and Nongalactic Astrophysics;Solar and Stellar Astrophysics