  We describe the most general nature of accretion and wind flows around a
compact object and emphasize on the properties which are special to black hole
accretion. The angular momentum distribution in the most general solution is
far from Keplerian, and the non-Keplerian disks can include standing shock
waves. We also present fully time dependent numerical simulation results to
show that they agree with these analytical solutions. We describe the spectral
properties of these accretion disks and show that the soft and hard states of
the black hole candidates could be explained by the change of the accretion
rate of the disk. We present fits of the observational data to demonstrate the
presence of sub-Keplerian flows around black holes.
