Understanding an octave in music:

In music there are measures of sounds, a good example would be the piano. A standard piano has 88 keys. The middle key on an 88 keys piano is know as middle C. If you want a higher pitch of sound you play going towards your right. To better describe an octave it is good to note intervals or measures of eight keys in accordance to frequency going higher or lower and the octave being the section. An example would be on a piano, "CDEFGABC," in this example the two Cs would be an octave apart leaving the two Cs of the same pitch class and this being a section on the piano. This will give you some understanding of the octave as intervals in music or sections of measures when reading music.