Music Theory

[last updated: 2026-09-04]
Disclaimers
Scales
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ROUGH, INCOMPLETE, EDIT IN PROCESS......

• Circle of Fifths:
  • The Circle of Fifths (COF) is a diagram that shows relationships between keys and chords.
    It can be used as an aid to composition or improvisation, because it can show you what chords will work well with other chords.

    
    My intention/goal here is to show how it is derived/built, and how to use it.

    
    move this to a separate page...

  • So, starting from the beginning:
    The COF is designed in relation to Western music, which is based on a standard piano keyboard.
    • A standard keyboard has 88 keys.
      [insert image here]
      The term 'key' has multiple meanings.
      This is the first meaning, and designates a physical element, plastic or ivory, either white or black, that you press to create a sound.
    • Each key is named, a letter from A to G, with extra modifiers ('sharp' or 'flat') for the black keys.
      [insert image here]
      A symbol is used when you want to refer to a 'sharp', so that you don't have to spell out the whole word:
      '#'

      The symbol used to designate a 'flat', is:

      '♭'
    • Notes: are the sound produced by the piano when you press a key.
      They are named the same as the names of the keys.
      The note/sound produced when you strike a key has a given frequency or pitch.
      For example, the A above middle C on the keyboard (also designated A4) produces a frequency of 440 Hz.
      This note has been designated as an international standard that musicians and orchestras use to tune their instruments.
    • Octaves:
      • An octave is a set of 12 sequential keys/notes.
        [insert image here]
      • The frequency/pitch of a given note is exactly half the pitch of the same named note 1 octave higher.
    • Intervals:

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