''Milestones'' is an album recorded in February and March 1958 by Miles Davis. It is renowned for including Miles' first forays into the developing modal jazz experiments, as noticed on the piece "Miles" (not to be confused with "Milestones" - recorded, by Davis, in 1948), which would be followed to its logical conclusion on ''Kind of Blue''. Furthermore, the playing of his sextet, which featured Cannonball Adderley and John Coltrane contributing on such tracks as "Straight No Chaser", have induced it to be highly regarded by jazz musicians, fans and critics alike. It was also the last time the rhythm section of Jones, Garland and Chambers would ever play with Miles on record.
Coltrane returned to Davis’s group in 1958, contributing to the “modal phase” albums ''Milestones'' (1958) and ''Kind of Blue'' (1959), both considered essential examples of 1950s modern jazz. Davis at this point was experimenting with modes—i.e., scale patterns other than major and minor. - Wikipedia