  The study of formation and evolution of galaxies is reviewed, making emphasis
on the physical factors which are important to understand the origin of the
galaxy Hubble sequence. We concentrate on predictions of the hierarchical Cold
Dark Matter (CDM) scenario and the confrontation with observations. The mass
assembling of the CDM halos, the baryonic processes within them, and the
evolution of disks and spheroids are described. The successes and shortcomings
are discussed. Disk evolution seems to be a quiescent and extended process
driven by the cosmological initial conditions, while spheroids are formed
probably in violent events, where several astrophysical processes are
competing.
