An octave is a musical interval that spans eight notes in a scale. In Western music, when you move from one note to another note that is eight steps higher or lower, you have completed an octave. For example, if you start on the note C and go up to the next C after seven other notes, you have moved through an octave. Octaves are important in music because they create a sense of harmony and balance. Instruments like the piano and guitar utilize octaves to produce richer sounds. The concept of octaves is also fundamental in music theory, helping musicians understand scales and chords.