  We review the current understanding of accretion flows around compact objects
with a special emphasis on advective disks. We discuss the influence of the
centrifugal pressure supported high density region around compact objects
(where shocks may also form) on the emitted spectra. We show that the
stationary and non-stationary spectral properties (such as, low and high
states, transition of states, quasi-periodic oscillations, quiescent and rising
phases of X-ray novae, etc.) of both low mass and supermassive black hole
candidates could be satisfactorily explained within the framework of the
analytical solution of the advective disks without invoking any ad hoc
components such as Compton clouds or magnetic corona.
