Played in a musical ensemble such as through electronic music, rap or 'drum and bass' on a computer, or via an orchestra, such notes are frequently used to provide a counterpoint or counter-melody, in a harmonic context either to outline or juxtapose the progression of the chords, or with percussion to underline the rhythm. In popular music the bass part most often provides harmonic and rhythmic support, usually playing the root or fifth of the chord and stressing the strong beats. "The bass differs from other voices because of the particular role it plays in supporting and defining harmonic motion. It does so at levels ranging from immediate, chord-by-chord events to the larger harmonic organization of a entire work.". Several lower-pitched instruments are often classified as bass instruments, but in fact any instrument playing the lower of two or more parts is providing the 'bass' in a given piece of music; conversely, instruments generally classed as bass instruments may not actually be playing the bass line where they are used.
In classical music, different forms of bass are: basso concertante, or basso recitante; the bass voice of the chorus; the bass which accompanies the softer passages of a composition, as well as those passages which employ the whole power of the ensemble, generally played by the violoncellos in orchestral music; contrabass (“under bass”), is described as that part which is performed by the double basses; violoncellos often play the same line an octave higher, or a different melodic or rhythmic part which is not a bassline when double basses are used; basso ripieno; that bass which joins in the full passages of a composition, and, by its depth of tone and energy of stroke, affords a powerful contrast to the lighter and softer passages or movements.