Study of Accretion Processes on Black Holes: Fifty Years of Developments

Fifty years ago, in 1952, the first significant paper on accretion flows was written by Bondi. The subject has grown exponentially since then. In fact, today many of the satellites engaged in space physics research look for signatures of accretion processes in whatever objects are studied. In this review, I will touch upon the significant developments in these years in this subject, emphasizing mainly on accretion onto black holes. Since winds and accretions are generally studied under similar framework, some references of the winds/outflows studies will also be made.