Physical Processes behind the Morphological Hubble Sequence

The study of formation and evolution of galaxies is reviewed, with emphasis on the physical factors which are important to understand the origin of the Hubble sequence. We concentrate on predictions of the hierarchical Cold Dark Matter (CDM) scenario and their 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.