Anthony Braxton is often thought of as a jazz saxophonist. That description doesn't begin to scratch the surface of what he does. He's a saxophonist (sopranino to contrabass), clarinetist (high E flat to contrabass), flutist, and pianist. He plays jazz, but not just jazz. He's a composer - of jazz, but not just jazz. He has written chamber music (often involving improvisation), operas, and a piece for four orchestra. His concepts have gotten more complex over the years, to the point where his musicians often interpolate material from other Braxton compositions when performing his music.
Five Pieces 1975 was the second release in his contract with Arista Records, who were having one of those brief flings with avant-garde jazz that major labels go through periodically. This is relatively early Braxton, and most of the music is identifiably jazz, albeit of a pretty advanced variety. Braxton's quartet here was one of his great ensembles - Kenny Wheeler on trumpet and flugelhorn, Dave Holland on bass, and percussionist Barry Altschul. Braxton's music requires virtuoso musicians, and he has them here.
One of Braxton's quirks is that he titles his pieces not with words, but with formulas, symbols, drawings, and combinations of the above. At some point he realized that his method made verbal references to any particular piece difficult, so he started numbering them as well. Here's Composition 40M, which made a huge impression on me as a young man. Braxton's graphic title is to the right.