A quarter tone is a musical interval that is half the size of a semitone, which is the smallest interval in Western music. This means that there are 24 quarter tones in an octave, compared to the 12 semitones typically used in Western scales. Quarter tones are often found in various musical traditions, including Middle Eastern and Indian classical music, where they add unique flavors and expressiveness to melodies. In Western music, quarter tones are less common but can be used in contemporary compositions and experimental music. Composers like Charles Ives and Olivier Messiaen have explored quarter tones to create new soundscapes. Musicians may use special instruments or techniques to produce these intervals, expanding the possibilities of musical expression.