Quarter tones are musical intervals that are half the size of a standard half step, dividing the octave into 24 equal parts instead of the usual 12. This allows for a richer palette of pitches, creating unique sounds that are not found in traditional Western music. Quarter tones are commonly used in various musical traditions, including Middle Eastern music and Indian classical music. In Western music, quarter tones are less common but can be found in contemporary compositions and experimental genres. Musicians may use special instruments or techniques to produce these pitches, expanding the possibilities for melody and harmony. Composers like Charles Ives and Olivier Messiaen have explored quarter tones in their works.