Quasars and their host galaxies I quasar e le loro galassie ospiti

This thesis is intended to give a general overview of one of the most forestanding research field of modern astrophysics: the quasar phenomenon. A description of the optical-UV spectroscopic properties and the spectral energy distribution is presented, followed by a discussion of the basic accretion mechanism and the different accretion modes. Then the thesis concentrates on the classification scheme of the FourDimensional Eigenvector 1 parameter space. The morphological properties of quasar hosts are also described. Finally, the thesis suggests a possible way to organize future morphological studies in the search for a connection between host morphology and the 4DE1 quasar sequence.