Triads

A triad is the smallest chord there is: three notes, a root, a third and a fifth. The third decides everything — a major third makes it major, a minor third makes it minor — and the fifth is the same in both. Every chord you know is a triad with something added or doubled: an open guitar chord is a triad spread over six strings, a piano chord a triad under one hand, a seventh chord a triad with one more note. Take the extras away and what is left is small enough to play anywhere, in a dozen places, on any instrument.

Above is C major, every note of it, everywhere on the guitar; the capsule switches to minor, the root chip changes the key, the picker the instrument, and the shape menu draws one grip at a time. The presets beneath open the same figure on the inversions and the open voicings. The figure follows the text from here.

Three notes, everywhere

The notes above are the whole chord: every C, E and G on the instrument. Any three of them close enough for one hand make a C major triad — a big chord shape is just a particular choice of five or six of them. Tap a note to hear it; change the root and the same pattern shifts, because a triad is a shape before it is a set of note names: 1, 3 and 5, wherever the 1 is.

Stacked in thirds

C, E, G: the thirds stacked

Take a note, skip one, take the next, skip one, take the next: a triad is two thirds stacked, and the size of the thirds is the quality. Major third under minor third — four semitones, then three — is a major triad; minor under major is a minor triad; two minor thirds is diminished, two major augmented. The wheel shows the stack; the instrument shows where it lands.

Minor is one note lower

Major to minor: the third moves

Lower the third a semitone and the chord is minor: C E♭ G. Everything else stays — the root, the fifth, the shape's outline. On a string instrument that is one finger moved back a fret; on a keyboard one key to the left. Learn the major shapes and you have learned the minor ones; the difference is which note you bend down, and it is the difference the ear cares most about.

Big shapes, small shapes

Set the shape menu to "Basic shapes" and the explorer draws one grip of C, the halo on its notes and an outline joining them; ‹ › walks the grips up the instrument. On a guitar these are the five open-chord forms moved up the neck, the CAGED shapes — landmarks, but a handful, slow to move. Inside each is a small triad, three strings, one note each, that says the same chord in a quarter of the space; the inversions page is those, and the open voicings page the ones spread wider than an octave.

The triads of a key

A key has seven notes and, stacked in thirds on each, seven triads — the chords its songs are made of. In C major: C, Dm, Em, F, G, Am and B diminished. The figure has flipped to the nest, each chord inside the scale it comes from, so you can see that a chord is the key with four notes left out — and that the next chord is one step over, not somewhere else. A I–vi–IV–V is four small shapes within reach of one position. Chords in a key is the page for it, with a page for every key.

On the guitar

C major on the guitar: the five CAGED forms are triads with the notes doubled across six strings; the three-string triads on the top strings are what players actually move. Three shapes per string set, walking up the neck in order.

On the piano

C major on the piano: three keys under one hand — thumb, middle finger, little finger in root position — and the inversions are the same three keys with the hand moved up one note. A triad on a piano is the clearest picture of the stack there is: skip a key, skip a key.

On the ukulele

C major on the ukulele: four strings, so every chord is a triad with one note doubled, and the high G string means the "lowest" string is often not the bass. The shapes are small and close; a ukulele triad moves up the neck as easily as a guitar's three-string one.

On the bass

C major on the bass: a bass player outlines the triad more than strums it — root, fifth, third in turn — and the shape is one box, the same on every pair of strings.

On the mandolin

C major on the mandolin: the fifths tuning puts the root and fifth on adjacent courses at the same fret, the third two frets along — the chop chord's skeleton.

Hearing them

The app's harmony games are this page by ear: a chord sounds, you hear which degree it is, you find its shape with the root shown — the triads of a key in order, then any triad on any root, then the inversions. The shapes are never memorized as pictures; you build them from the root and the degrees, which is why they come out the same on a ukulele or a piano. Build Shapes is the browser version, no microphone.