Where the chord's notes are in the first few frets. This is a map of the notes, not a hand shape to play: Chords on the Guitar shows real shapes.
A chord is three or more notes played together. The simplest and most common chords have three notes. They're called triads.
A triad is two 3rds stacked on top of each other. A 3rd can be big (a Major 3rd, 4 ) or small (a minor 3rd, 3 half steps), so there are four ways to stack two of them: the four kinds of triad below. Which kind a chord is (major, minor, augmented or diminished) is called its quality.
Pick a root note and a triad at the top of the page to see its notes on the guitar and hear it.
Start on any note: the root. Add a middle note a above the root, and a top note a minor 3rd above that. We call the three notes the root, the 3rd and the 5th, after their distance from the root.
A Major 3rd is 4 half steps, and a minor 3rd adds 3 more. So the 5th is 7 half steps above the root: a . Measured from the root, a major triad is a root, a Major 3rd and a Perfect 5th. It sounds bright and settled.
Its formula is 1 3 5. The numbers are of the major scale. A ♭ means a half step lower, a ♯ a half step higher. In C major, 1 3 5 is C E G.
A minor triad stacks the same two 3rds the other way round: a minor 3rd first, then a Major 3rd. So it has a root, a minor 3rd and a Perfect 5th. Its formula is 1 ♭3 5.
Only the 3rd is different, one half step lower than in the major triad. But that small step changes the mood: major sounds bright and happy, minor sounds darker and sadder.
An augmented triad stacks two Major 3rds. It's a major triad with its 5th raised by a half step (8 half steps from the root, an 5th). Its formula is 1 3 ♯5.
Augmented chords sound tense and unsettled, so they're less common, but they add an interesting touch.
A diminished triad stacks two minor 3rds. It's a minor triad with its 5th lowered by a half step (6 half steps, a 5th, also called the tritone because it spans three ). Its formula is 1 ♭3 ♭5.
It sounds tense and wants to move on. You'll meet it as the chord on the 7th note of every major key.
A chord is named after its root. A letter on its own means major (C). Add m for minor (Cm), ° (or dim) for diminished (C°), and + (or aug) for augmented (C+). These short names are called chord symbols.
Next: Suspended Triads