A saxophone has a conical metal (originally brass) tube with about 24 openings controlled by padded keys; the mouthpiece is similar to that of a clarinet. Two octave key vents allow the instrument to overblow to a higher register at the octave. Except for the sopranino and one form of the B♭ soprano saxophone, built straight like a clarinet, saxophones have an upturned lower end and a detachable crook, or neck, at the upper end.

The normal compass originally extended from B (B below middle C) to f‴ (the third F above middle C), but it soon was expanded downward one half step to include B♭. The compass of the most commonly used members of the saxophone family has been further increased: the alto and tenor can sound one half step above f‴, and the baritone can sound one half step below B♭. The compass is pitched differently for each member of the family: the B♭ soprano, a tone lower than written; the E♭ alto, a sixth lower; the B♭ tenor (made with an undulating crook), a ninth lower; the E♭ baritone (with a looped crook), an octave below the alto; and the B♭ bass (similar in shape to the baritone), an octave below the tenor. Rare forms, representing the extreme ranges of the instrument, include the sopranino, contrabass, and subcontrabass saxophones. All of the common forms were originally pitched in C or in F; the C melody saxophone, a tenor in C, is occasionally used for playing vocal music without transposition.

The saxophone has great flexibility, blending well with both brasses and woodwinds. It is not widely used as a concert instrument but is quite prominent in jazz, in which it is a principal vehicle for melodic improvisation. Among the greatest jazz saxophonists have been Lester Young (Young, Lester), Coleman Hawkins (Hawkins, Coleman), Charlie Parker (Parker, Charlie), Sonny Rollins (Rollins, Sonny), Ornette Coleman (Coleman, Ornette), and John Coltrane (Coltrane, John).