Music Theory

[last updated: 2026-09-18]
Disclaimers
Scales
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ROUGH, INCOMPLETE, EDIT IN PROCESS......

• Gotchas:
  There is one thing that makes music theory hard to understand for beginners:
  There is more than one name for most things, whether keys or chords or whatever.

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• The Basics:
  • It's helpful to learn music theory using a standard piano keyboard as a reference.
    A standard keyboard has 88 keys. A lot of electronic keyboards have fewer, perhaps 32 or 49 or 61.
    A "note" or sound of a certain pitch or frequency is produced when you press a key.
      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.
  • Keys are named:
    • White keys are named a letter from A to G (..., then repeating, starting over with A for the next white key as you go up the keyboard,)
    • Black keys - "sharps" and "flats":
      • Black keys are named in reference to the white key that's next to them.
        The name of a black key will always have two parts:
        The first part will be the name of the white key that you're using as a reference.
        The second part will either be "sharp" or "flat"
        If the black key is higher in pitch than its reference white key, it will be a sharp.
        Sharp symbol: '#'

        If the black key is lower in pitch than its reference white key, it will be a "flat".

        Flat symbol: '♭'

        So for example, the black key just to the right (higher in pitch) of the C key will be a C#.
        And the key just to the left (lower in pitch) of the C key would be C♭

        However the key to the left of a C is a B, since there is no black key right next to a C on the left side.
        This is one of those cases where two different names can be used for the same key.
        Although you would almost never see it this way, the fact is that the B key could legally be called a C♭
  • Intervals - semitones:
    • Semitones are a measure of distance between two notes.
      Two notes on the keyboard that are right next to each other,
      that is, there are no other keys, either white or black, in between them,
      are said to be "1 semitone apart."
      One semitone is also called a half step.
    • So for example, there is 1 semitone between a C and a C#,
      and there are two semitones between a C and a D.
      Two semitones is also called a whole step.
  • Octaves:

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  • The C-major scale

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    Un-edited below here...
    

  • Octaves:
    • An octave is a set of 12 sequential keys/notes, including all white and black keys until you return to the starting note.
      [insert image here]
    • The frequency/pitch of a given note is exactly half the pitch of the same-named note 1 octave higher.

• The first way that semitones are used is to construct scales of a certain type.
  • Two different scales of the same type, for example C-major and F-major,
    will have the same pattern of semitone intervals between their notes.
  • If, for example, you start with the C-major scale,
        C, D, E, F, G, A, B
    and count the number of semitones between the notes,
    you get this sequence (starting from the distance between C & D, ending with the distance between B and the next octave C):
        2, 2, 1, 2, 2, 2, 1
    By definition: all major scales, regardless of key/tonic,
    have this same pattern of semitone intervals between notes.

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