Post-bop is a blanket term for much of the swing-driven small-group jazz that’s been produced since the mid-'60s, where musicians cling to fundamentals of hard-bop that were cemented in the '50s while simultaneously experimenting with unusual harmonies, mixed meters and polyrhythms, and exploratory structures. Its greatest practitioners are at once steeped in jazz tradition while committing themselves to forging new sounds. The term makes room for so much: the probing modal jazz of John Coltrane; the mercurial, whipsaw motion of sax player Eric Dolphy; the wide-open experiments of the second Miles Davis Quintet with Herbie Hancock and Wayne Shorter; the swinging free jazz of Ornette Coleman; the meditative chamber improvisation of The Jimmy Giuffre 3. Naturally, musicians have never stopped building on these ideas—the 2010s have delivered richly in the form of Ambrose Akinmusire's moody hybrids, JD Allen's searching, relentlessly swinging forms, and Vijay Iyer Trio's elastic reinventions.