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We describe the evolution of models of accretion disks around black holes. We emphasize the importance of centrifugal barrier supported quasi-spherical dense boundary layer (CENBOL) surrounding black hole that is being recognized in recent times. Most of the current observations, such as the hard to soft state transition, quasi-periodic oscillations, power-law spectral slope in soft states, almost constancy of power-law slopes in both hard and soft states, pattern of the rise and fall of intensities in X-ray novae and processes and rates of mass outflow could be easily understood using the advective disk model which includes this barrier.