 Around that same time, a move towards structural simplification of bebop occurred among musicians such as Horace Silver and Art Blakey, leading to the movement known as hard bop.Development of jazz would occur through the interplay of bebop, cool, post-bop, and hard bop styles through the 1950s.Bebop differed drastically from the straightforward compositions of the swing era and was instead characterized by fast tempos, asymmetrical phrasing, intricate melodies, and rhythm sections that expanded on their role as tempo-keepers.