This is a chart...

[dwest2419]

This is a chart to show how those chords are related C D E F G A B

Tonic

C major C E G / E minor E G B / A minor A C E

Sub-dominant

D minor D F A / F major F A C

Dominant

G major G B D / B dim B D F

As you can see A min and C maj share two notes C and E
As you can see C maj and E min share two notes E and G

As you can see D min and F maj share two notes F and A
As you can see G maj and B dim share two notes B and D

As you can see this chart help me out with chord progressions and how you can use substitutions for them.

Check it out:

All tonic - subdominant - dominant progression

iii-IV-vii
iii-ii-vii
iii-ii-V
iii-IV-V

I-IV-V
I-ii-V
I-ii-vii
I-IV-vii

vi-ii-V
vi-IV-V
vi-ii-vii
vi-IV-vii

I was wondering where that IV-V-vi come from.

[Malcolm]

I was wondering where that IV-V-vi come from.

As vi likes to move to a sub dominant chord (ii or IV) you have yourself a little loop. But, it really does not go anywhere.

Not sure what you are getting at?

[dwest2419]

Yea, you're right I noticed that. But if that's what you're looking for in music subdominant to dominant to tonic. Like I said each one has there own mood.