An octave is a musical interval that spans eight notes in a scale. It is the distance between one musical pitch and another with double its frequency. For example, if a note has a frequency of 440 Hz, the note an octave higher will have a frequency of 880 Hz. Octaves are fundamental in music theory and are used in various musical scales, including the major scale and minor scale. In Western music, octaves are divided into twelve semitones, which are the smallest intervals used in this system. This division allows for the creation of different musical chords and harmonies. The concept of octaves is also important in the study of acoustics and the design of musical instruments, as it affects how sounds are produced and perceived.