Introduction to Harmony on Guitar
An introduction to the fundamentals of major key harmony by exploring the guitar fretboard through interactive animations and sound.
Core concepts
What is harmony?
Harmony is the sound of multiple notes played together, like chords and chord progressions. It contrasts with melody, the sound of individual notes played one after another.
Harmony describes which notes and chords sound good together, and how to evoke certain feelings with certain combinations of sounds.
What are triads?
Triads are the most common type of chord in Western music, and the foundation of more complex chords.
Triads are three-note chords built by stacking "third" intervals.
What are intervals?
Intervals are the building blocks of harmony. An interval is the difference in pitch between two notes.
There are 12 basic intervals in Western music. The names of the intervals, like "major third" or "perfect fifth", can be derived from the major scale.
Major scale intervals
Western harmony is based around the major scale. It's the source of interval names, chords, and chord progressions.
The easiest way to visualize a scale is in a straight line. Press play in the interactive diagram to see and hear the major scale intervals on a single guitar string.
Optional detail for the curious.
You don't need to know any of this to understand the rest of the lesson.
Major scale degrees
The numbers in the diagram give the order of the notes in the scale, or scale degrees. In a major scale, the scale degrees match the names of all the major and perfect intervals.
The 1 is the reference point from which the intervals are measured. The 1 of a scale is called the tonic. The 1 of a chord is called the root.
Major scale formula
The best way to remember the major scale formula is that it has "semitones" between 3-4 and 7-1.
In other words, there are two frets between most notes, but there is only one fret (a "semitone" or "half-step") between the 3rd and 4th notes, and between the 7th and octave.
Optional detail for the curious.
You don't need to know any of this to understand the rest of the lesson.
Interval names
Interval names have two parts: a quality (like "major") and a number (like "third").
The interval number is the number of letter names from one note to the next in the musical alphabet. The interval from C to D is a second, from C to E is a third, etc.
Perfect intervals
The quality of fourth, fifth, octave, and unison intervals is called perfect, because the sound waves of the two pitches vibrate together in an overlapping and mathematically simple way. That makes them sound especially consonant.
Major and minor intervals
The quality of the remaining intervals is called major or minor. Major intervals are those in the major scale, and minor intervals are one fret behind them.
Minor intervals can be written with a "flat" symbol, like "b3" for minor third.
Interval colors
Each of the intervals can be associated with one of the 12 colors in the chromatic color wheel. This aids learning by engaging both sides of the brain. Don't worry about memorizing the colors, they work subconsciously.
Learn more
Tap around the fretboard in the diagram to explore other intervals.
For more detail about intervals, see the Introduction to Western Harmony chapter of the Fretboard Foundation book.
Major triads
Major triads are the most common chords in Western harmony. They're the most stable and consonant type of chord.
A major triad is a three-note chord made of a root note, a major third, and a perfect fifth (the 1-3-5 of a major scale).
Example major triad chord
On guitar, chord shapes find the triad notes on different strings and in various octaves, depending on what is convenient and comfortable.
Play the interactive diagram to see how an example E major chord shape is assembled from the major triad intervals.
Minor triads
Minor triads are the second most common type of chord in Western harmony. They tend to sound darker and moodier than major chords.
A minor triad is the same as a major triad with the third lowered one fret to a "minor third", written "b3" ("flat 3").
Remember: major chords have a major third, and minor chords have a minor third.
Play the diagram to compare major and minor triad sounds.
Example minor triad chord
Here's an example of an E minor chord shape assembled from the minor triad intervals.
Harmonizing the major scale
What chords sound good together?
Most songs are composed in a "key", like "C major", which names a scale.
The chords that sound good together in a key are those made from notes of the scale. Assembling all the chords in a scale is called "harmonizing the scale".
Where do chords come from?
Stacking thirds
Chords are constructed by "stacking thirds" on each note of the scale. That means starting from the root note and then adding every other note in the scale (every "third" note) until the chord has as many notes as we want.
Play the interactive diagram to explore how an example E major scale is harmonized.
More about harmonizing scales...
Optional detail for the curious.
You don't need to know any of this to understand the rest of the lesson.
Roman numerals
Chords are numbered using roman numerals (I, V, etc.) that match the scale degree. Uppercase roman numerals represent major chords, and lowercase represent minor chords.
Chord types in a major key
Chords will be different types depending which scale degree they start on. When the distance between a chord's first two notes is 4 frets (a major third), it's a major chord. When it's 3 frets (a minor third), it's a minor chord.
In a major key:
- The I, IV, and V chords are always major.
- The ii, iii, and vi chords are always minor.
- The vii chord is a diminished triad (about which, more later).
Learn more
For more information, see the Major Key Harmony chapter of the Fretboard Foundation book.
Changing keys
The diagrams above are all in the key of E major, because the 1 of the scale is placed on the open E string.
To change to another key, just move the 1 to a different note, sliding the entire scale pattern with it. When you run out of frets going up the fretboard, wrap the pattern around to find the same notes in a lower octave, 12 frets below.
This is called transposing to another key. Experiment with changing keys in the interactive diagram (using and ) to see how the same pattern is transposed to a different fret.
Optional detail for the curious.
You don't need to know any of this to understand the rest of the lesson.
The intervals in the diagram that appear behind the 1 are technically called inverted intervals.
Intervals are measured ascending
Intervals are always measured from the lower pitch to the higher.
Dropping down an octave
When the higher pitched note is dropped down an octave (becoming a lower pitched note), it will still sound like the same note to human ears. But the actual interval distance between the two notes will then be different, as you may have noticed in the diagram.
Inverted intervals
Because we hear two notes an octave apart as the same note, it's somewhat counterintuitive that the interval from the lower to the higher pitch is different than the interval from the higher to the lower. The descending interval is an "inversion" of the ascending interval.
Harmonic convenience
For purposes of harmony, inverted intervals work more or less the same as the originals, and they can be used interchangeably.
Inverted intervals are commonly used in guitar chord shapes, because they are often found in more convenient locations.
All triad chords in a major key
Putting it all together, we can harmonize all possible triad chords in any major key on the entire fretboard.
Caution: this diagram can be overwhelming. Try to pull back and see the big picture, without needing to understand every detail. Then focus on exploring a few small parts at a time.
Related material
Interval Color Wheel
What's with all these interval colors?
Position Player
A study tool for exploring CAGED shapes on the fretboard.