What is a key?

Put simply a key is a collection of notes to be used to make some music.

What is usually meant by the key of a piece of music is which major or minor scale is being used.

For example, if I write a piece of music using the notes C, D, E, F, G, A and B and I focus on that C (I keep coming back to that note, or I use that note in a prominent way), then I’ve written a piece is C major.

If I use G. A, B, C, D, E and F# (the note one fret higher than F) then I’m in the key of G major.

What is a minor key?

A minor key occus where there is a note in the scale that is 3 frets higher (a tone plus a semitone) than the starting note of the scale.  So if your starting note is A and you’ve got a C in your key then you will be playing in A minor.

I can make this happen by taking a major scale and then flattenning the 3rd note of the scale.  So I could take C major, and just flatten the third to Eb and that would give me a C minor scale.

This covers all sorts of situations where you might be playing mode 2, 3, 6 or 7 of the major scale (the dorian, phrygian, aeolian, or locrian if you like the Greek) or even making up your own scale.

What is usually meant by a minor key?

Modes 2, 3, 6 and 7 of the major scale are all minor because they all have their third note a tone plus a semitone above their first note.

The one people are usually referring to, especially in a classical music context, is the 6th mode.  The sixth mode of a major scale can also be called the Aeolian mode or the Natural Minor.

Usually when we talk about a minor key we are talking about using a scale starting from the sixth note of a major scale.

Relative major and relative minor

To find the relative minor of a major scale we just take the notes of a scale:

C major              C   D   E   F   G   A   B   C

and then just start from the sixth note:

                                                      A   B   C   D   E   F   G   A

you’re playing a minor scale.

Here we say that A minor is the relative minor of C major.

C major is the relative major of A minor.

How to find the relative major or minor

On the guitar you can just move 3 frets – a tone plus a semitone (also known as a minor third).

To find the relative minor just move down 3 frets.  Don’t forget you can use this chart to help you with finding and naming notes.  For example to find the relative minor of C major, think of the C, move down 3 frets and that will be the starting note of the relative minor – A minor.  Three frets down from B is G#, so G# minor is the relative minor of B major.

How to play the natural minor

There is no difference between the notes of the major scale and its relative minor scale so there are no new shapes to learn – you just hear the notes you’re playing differently and focus on different notes depending on what chord is being played.

The next thing to learn about is the Harmonic minor.