Music Theory for Guitar
Music theory isn't a rulebook — it's the pattern behind why songs work. These short, plain-English guides explain the core ideas, and each one links straight into a free interactive fretboard so you can see and hear it, not just read it.
Whether you play guitar or piano, the same handful of ideas explain almost everything: how chords are stacked, how scales give you a key to play in, how the circle of fifths ties keys together, what intervals are, and how to train your ear to recognise them. Start anywhere:
What a chord really is, how triads and 7ths are built, and why major and minor feel so different.
Roman numerals and the handful of progressions — I–IV–V, I–V–vi–IV, ii–V–I — behind most songs.
How music stops, pauses and pretends to stop. Hear any two endings back to back and see why V–I lands when IV–I doesn't.
Stack one more third on a triad and hear what changes: why maj7 floats, why 7 shoves, and why a key holds exactly one dominant seventh.
The major scale as the ruler for everything, how modes work, and how scales map onto the fretboard.
Five notes, one easy shape — the forgiving scale nearly every guitarist solos with first.
The one diagram that explains keys, key signatures, and which chords belong together.
The distances between notes — the atoms that every scale, chord and melody is built from.
The small three-note shapes behind every chord — inversions, string sets and the voice-leading trick.
What C/E, C/G and D/F# really mean — slash chords, walking bass lines, and the grips guitarists actually use.
Why five shapes tile the whole neck, always in the same order, repeating at fret 12 — the machinery explained.
The open strings, the 12th-fret reset and octave shapes — how to read any note on the neck.
How to actually hear intervals, chords and scale degrees — the skill that separates musicians.
Every concept here becomes obvious the moment you see it on the neck and hear it. That's what the interactive tool is for — light up any chord or scale, explore the circle of fifths, and drill your ear, free in your browser.
Reading only gets you so far — open the interactive fretboard and watch these ideas light up on guitar and piano.
Enter the tool