Hard bop is a subgenre of jazz that is an extension of bebop. Journalists and record companies began using the term in the mid-1950s Jazz critic Scott Yanow distinguished hard bop from the broader world of bop by saying that "[t]empos could be just as blazing but the melodies were generally simpler, the musicians (particularly the saxophonists and pianists) tended to be familiar with (and open to the influence of) rhythm & blues and the bass players (rather than always being stuck in the role of a metronome) were beginning to gain a little more freedom and solo space."
Hard bop has been seen by some critics as a response to cool jazz and West Coast jazz.
Michael Cuscuna maintains that Silver and Blakey's efforts were in response to the New York bebop scene:
<blockquote>Both Art and Horace were very, very aware of what they wanted to do. They wanted to get away from the jazz scene of the early '50s, which was the Birdland scene—you hire Phil Woods or Charlie Parker or J. J. Johnson, they come and sit in with the house rhythm section, and they only play blues and standards that everybody knows. There's no rehearsal, there's no thought given to the audience. Both Horace and Art knew that the only way to get the jazz audience back and make it bigger than ever was to really make music that was memorable and planned, where you consider the audience and keep everything short. They really liked digging into blues and gospel, things with universal appeal. So they put together what was to be called the Jazz Messengers. and Carl Perkins, The broadening influence of hard bop coincided with a generation of jazz pianists who rose to prominence in the late 1950s – among them Tommy Flanagan, Kenny Drew, and Wynton Kelly – who took "altered" approaches to bebop. Although these musicians did not work exclusively or specifically within hard bop, their association with hard bop saxophone players put them within the genre's broader circle. West Coast Jazz's diminishing influence during the late 1950s accelerated hard bop's rise to prominence, while the transition to 33 rpm records facilitated the shifts toward longer solos that were typical of hard bop albums.
In 1956, The Jazz Messengers recorded an album titled Hard Bop, which was released in 1957, including Bill Hardman on trumpet and saxophonist Jackie McLean, with a mix of hard bop compositions and jazz standards. Shortly after, in 1958, The Jazz Messengers, with a new line-up including Lee Morgan on trumpet and Benny Golson on saxophone, recorded the quintessential hard bop album Moanin, Morgan's albums attracted rising stars in the jazz world, particularly saxophonists Joe Henderson and Wayne Shorter; Morgan formed a "long-standing partnership" with the latter. who would go on to become "a hard bop stylist." Blue Train was described by Richard Havers as "Coltrane's Hard-Bop Masterpiece", although an edit made to one of the album's tracks caused controversy following disapproval from sound engineer Rudy Van Gelder. In the early to mid-1960s, prior to his death, Coltrane experimented in free jazz but again drew influences from hard bop in his 1965 album A Love Supreme. Coltrane was a longtime member of Miles Davis' band, which bridged the gap between hard bop and modal jazz with albums such as Milestones and Kind of Blue. These albums represented a transition toward more experimental jazz, but Davis maintained core ideas of hard bop, such as the "call-and-response theme" found on one of Kind of Blue<nowiki/>'s best-known tracks, "So What". The earlier album Milestones was described as "indebted to hard bop" due to its "fast speeds, angular phrases and driving rhythms". Other hard bop musicians went to Europe, such as pianist Bud Powell (elder brother of Richie Powell) in 1959 and saxophonist Dexter Gordon in 1962. Powell, a bebop pianist, continued to record albums in the early 1960s, while Gordon's Our Man in Paris became "one of his most iconic albums" for Blue Note.
Other musicians who contributed to the hard bop style include Donald Byrd, Tina Brooks, Sonny Clark, Lou Donaldson, Blue Mitchell, Sonny Rollins, and Sonny Stitt.
David Rosenthal considers six albums among the high points of the hard bop era: Ugetsu, Kind of Blue, Saxophone Colossus, Let Freedom Ring, Mingus Ah Um, and Brilliant Corners, referring to these as being some of the genre's "masterpieces". Davis led other jazz musicians toward the fusion genre, particularly other trumpet players. For example, Donald Byrd's shift toward commercial fusion and smooth jazz recordings of the early 1970s, while celebrated within some circles, was considered a "betrayal" by fans of hard bop. His album Black Byrd (1973), Blue Note's most successful album, neared the #1 spot on the R&B charts despite the opposition of jazz purists.
In 1985, the filmed concert One Night with Blue Note brought together thirty predominantly hard bop musicians including Art Blakey, Ron Carter, Johnny Griffin, and Freddie Hubbard. Following fusion's decline, younger musicians started a bop revival known as neo-bop, the best-known proponent of this being trumpeter Wynton Marsalis. The revival was a "resurgence" by the 1990s, and by the 1990s, hard bop's revival had become so prominent that Yanow referred to it as "the foundation of modern acoustic jazz."