Deeper Dive into Basic Chord Theory

Often referred to as the "Nashville System"

Basic Chord Theory covers the following topics:

Once you have even a very basic understanding of these topics you will be surprised how this information will make your guitar playing simpler and more intuitive.

So let's begin...

What is a Chord?

A chord is a combination of three or more notes. Chords are used to accompany melodies and to create interesting harmonies that enhance the mood and impact a song is meant to create.

Chords can be played all at the same time, as for example, on a piano or guitar. Or the notes can be played individually with a slow strum, or played one after the other with a pick or with your fingers. This is usually called an arpeggio.


In its most basic form a chord is a triad containing three notes. For example, a C major chord consists of the notes C-E-G. These notes are the first, third and fifth notes (1-3-5) of the scale they are built on. On a guitar or piano, chords often consist of more than three notes. These additional notes are either instances of the basic notes, often an octave higher or lower. For example, the G chord at the open position is usually the first chord guitar players learn. Across all six strings the notes are G-B-D-G-B-G.

How are Chords, Scales and Keys Related

The "key" of a song is simply the root note of the scale the song is built on. So, for example, we say a song is in the key of D Major when the song is built on the D Major scale.

Specific chords are associated with the different notes of each major scale. And these chords also follow a specific pattern from key to key. This pattern tells us which chords sound good when playing along with songs in each key. The pattern is as follows:

Note 1 - Major Chord
Note 2 - Minor Chord
Note 3 - Minor Chord
Note 4 - Major Chord
Note 5 - Major Chord
Note 6 - Minor Chord
Note 7 - Diminished Chord

This means the pattern of chords from key to key is Major, minor, minor, Major, Major, minor, diminished. So, for the key of C for example, the chords that "fit", depending on which notes are used in the song are: C Major, D minor, E minor, F Major, G Major, A minor, B diminished.

Notice that the Major chords in this list are 1-4-5 (or I, IV, V). This is why we use the 1-4-5 chords in so many songs. These are the chords that "fit" the majority of notes in most songs.

The same pattern of chords is found in most popular songs. That pattern is what we call the 1-4-5 pattern where the chords used are predominantly the three major chords (1-4-5) with a sprinkling of minor chords thrown in here and there. The 7 chord (diminished) is rarely used.

The Bottom Line

The most important takeaway from all of this is that for strummng along with songs you should focus on the following:

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