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Guitar Chords Theory Lesson

Try to understand what you're playing on guitar. If you can relate it to simple piano chords, bass parts and singing it will really help.

Guitar chords and music theory

Playing piano or keyboard as well as guitar can really help you understand the instrument, as well as music theory in general. We're not talking about virtuoso skills here - even an hour or two will do the trick.

Guitar chords and theory -

If you start with a full barre chord shape, there are many smaller chord forms contained within the shape.We are playing six strings, but we only actually need three of them.

  • The first chord shown is a G chord, with a barre at the 3rd fret
  • (Fret 3 = G on strings 6 and 1)
  • Only three notes are needed to make a major or minor chord
  • As the guitar has 6 strings, there is a tendency to overuse them, and play them all!
  • The second chord picture shows the three notes of a G chord on strings 2, 3, and 4.
  • This is replicated on strings 1, 2 and 3 in the next picture.
  • Finally, a G5 or power chord is shown. This could be used instead of a standard G chord, especially in rock music.
  • These chord forms are completely movable - just move everything up 2 frets and you have A chords. (G is 2 frets lower than A)

Guitar Chords - deriving chords from barre chords


Minor chord forms

The second line of chord pictures shows the same idea, applied to minor chords

  • Both strings 1 and 6 are played at fret 5 = A.
  • An Am chord is formed with the notes A, C, and E
  • This chord is also found by playing just the 3 highest strings at fret 5 - only downside of this movable shape is that the root note is not at the bottom of the chord, which is generally a good idea.
  • If you are playing with another guitar or a piano, this is less important.
  • Moving all this up another 2 frets will give you Bm shapes, as shown in the next line of chord pictures.

Line 4, chord pictures

Now we are back to the same shapes as line 1, just moved up the fretboard, and the chord of C.

  • Move this info up another 2 frets, and we have chord shapes for D chords.
  • The last line shows minor shapes again, this time for Em chords.
  • Although the first shape could be played in frets 12 and 14, it's shown in 1st position as it can be difficult on an acoustic guitar if you are that far up the neck.
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Chords in G

Finally, these are not random chords - they are all from the harmonised scale of G, and will be found together in songs all the time. This theory is fully explained in my other hubs, but the simple facts are:

  • Every key has a unique set of 7 different chords, each based on the notes of the major scale.
  • For the key of G: G Am Bm C D Em F ♯m7b5
  • In the interests of simplicity, the last chord has been omitted. You can play this by using the Am cowboy chord, and adding fret 2 on string 6. (F♯)
  • You can use this set of chords for songwriting, and experimenting with this will really help you understand the guitar.

More chord forms


More chord forms

Here are some more practical applications:

  • Play the G shape shown, but loop your thumb around the neck to cover fret 3 on string 6.
  • Now we have a very flexible and movable shape, but with an added bass note to fill out the sound
  • String 5 is either muted with your thumb, or if you use finger picking you can avoid it.
  • Chord form for minor chords - a half barre, again the thumb covers string 6
  • This is one of the most useful chord forms, as it frees up other fingers to add extra notes on top of the chord.
  • G major scale pattern is shown - all these notes (2 Octaves) fit with all the chords shown.

Chords in the key of G





F♯ m7b5

Chord playing tips

Although you need to understand barre chords, it's not essential to use them all the time. In fact, I will go out of my way to avoid them because they are tiring, clunky and boring to listen to. See my other hubs on Barre chords for more detail. Three or 4 - note chords are the way to go, especially if you integrate them into lead playing by using arpeggios (Italian for like a harp.)

The Hendrix style of playing chords with your thumb over the neck instead of a full barre is the way I play mostly, hardly ever will I play a standard barre chord shape.

Eric Johnson is a master of chords and has some great mini lessons on Youtube at the moment. Lots of Hendrix influence going on there, taken to another level.

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