Basic Music TheoryIntroduction
The Major Scale
The basic chord in western music is a three-note chord called a triad. A triad is constructed by stacking thirds over the root of the chord. The distance between the bottom note and the top note is a fifth.
The bottom note of the chord is called the root; the middle note is the third, and the top note is the fifth.
In any given key, there is a set of chords that belong to that key. These are found by constructing a triad on each note of the scale, as follows:
In a major scale, three types of chords emerge:
A major chord consists of a major third and a minor third. The outer notes form a perfect fifth.
A minor chord consists of a minor third and a major third. The outer notes of a minor chord also form a perfect fifth.
A diminished chord consists of two minor thirds. The outer notes form a diminished fifth.
There is also an augmented chord, which consists of two major thirds, with the outer notes forming an augmented fifth, but this does not occur naturally within the major scale.
In a major scale, it is always the case that the I, IV and V chords are major (that is, the chords built on the 1st, 4th, and 5th notes of the scale), the ii, iii, and vi chords are minor, and the vii chord is diminished.
When representing chords by their scale degree (the note of the scale on which the chord is based), major chords are represented by capital Roman numerals; minor chords are represented by lowercase Roman numerals, and diminished chords are lowercase with a degree sign, as shown above. When representing chords by name, major chords usually have no suffix (or else the suffix "Maj"), minor chords have the suffix of "m" or "min", and diminished chords have a suffix of "dim" or the degree sign.
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