·         The C major scale goes like this:

C D E F G A B C¹ D¹ E¹ F¹ G¹ A¹

·         C¹ is an octave higher than C.  The key of C is used here as an example, but everything applies equally to all other keys.

·         The chord of C major (sometimes called the major triad) is C E G.  In terms of intervals, a major chord has the "formula" 1 3 5; using the generalised Roman numeral convention, the I major triad is I III V.

·         In a chord progression the C major chord is represented as C, or CΔ.

·         A chord to which extra notes have been added is expressed by adding the interval numbers to the basic chord symbol.  So C6 9 is the chord C E G A D¹

·         The dominant seventh is something in chord notation that can confuse the inexperienced.  You might expect C7 to be C E G B.  But in fact C7 represents C E G Bb.  Don't blame me - I don't make the rules!

·         C E G B is the major seventh chord of C and its symbol is Cmaj7, or CM7, or (most commonly these days) CΔ7.

·         Similar rules to those just described for chords in the major scale apply to the minor scale too.

·         The basic minor chord has the formula I IIIb V.  C minor is C Eb G and its symbol is Cmi or C-.

·         C Eb G A would be C-6.  C-7 is C Eb G Bb.  C-Δ7 (C minor-major seventh) is C Eb G B.

·         Notes added to major or minor chords can be sharpened or flattened and this is shown in the symbol.

·         For example C E G B D¹# F¹# has the symbol CΔ7 9# 11# (whew!).  C Eb Gb B D would be C- 5b Δ7 9.  C E G Bb D¹# A¹b = C7 9# 13b.  These are all real chords, used in jazz!