  We give a short introduction to the subject and review advances in
understanding the basic ingredients of the mean-field dynamo theory. The
discussion includes the recent analytic and numerical work in developments for
the mean electromotive force of the turbulent flows and magnetic field, the
nonlinear effects of the magnetic helicity, the non-local generation effects in
the dynamo. We give an example of the mean-field solar dynamo model that
incorporates the fairly complete expressions for the mean-electromotive force,
the subsurface shear layer and the conservation of the total helicity. The
model is used to shed light on the issues in the solar dynamo and on the future
development of this field of research.
