Essential Music Theory for Guitar

Music theory can feel overwhelming on guitar because information is often presented in isolated pieces: scales in one place, chords in another, and fretboard patterns somewhere else entirely. This page brings those ideas together so you can understand how guitar music actually works as a connected system.

Instead of memorising shapes without context, the goal here is to understand why notes, chords, and scales behave the way they do on the guitar. Once those relationships make sense, patterns stop feeling random and the fretboard becomes easier to navigate.

What music theory actually means on guitar

Music theory isn’t a separate subject from playing — it’s simply a way of describing the sounds you already hear and use. On guitar, theory helps explain:

  • Why certain notes sound stable while others want to resolve

  • How chords are built from scales

  • Why progressions sound “finished” or unresolved

  • How scales connect across the fretboard

When these ideas are clear, learning new material becomes much faster because everything relates back to the same few core concepts.

The core building blocks you need first

Almost all guitar music can be understood using a small set of fundamentals. The lessons on this page focus on these essentials:

  • Notes and intervals – the distance between notes and how they create tension or stability

  • Scales – organised sets of intervals that define the sound of a key

  • Chords – groups of notes taken from scales and stacked in specific ways

  • Keys and harmony – how chords relate to one another within a key

If these foundations are solid, more advanced topics like modes, substitutions, and improvisation make much more sense later on.

A common mistake guitarists make

Many guitarists learn theory as disconnected shapes: scale boxes, chord grips, and patterns that work — but only in isolation. This often leads to:

  • Getting stuck in the same positions

  • Not knowing which notes to target when soloing

  • Understanding what to play, but not why

The fix isn’t more memorisation. It’s learning how notes, intervals, and chords are linked across the fretboard.

How to use this page effectively

The videos below are designed to be watched in order, but you don’t need to master everything at once. A good approach is:

  1. Watch one lesson and focus on the main idea

  2. Pause and apply it to a simple chord or scale you already know

  3. Move to the next video once the concept feels familiar

  4. Revisit earlier lessons as your understanding improves

This page works best when used as a reference you come back to, rather than something you rush through once.

Video lessons

The lessons below walk through essential music theory concepts step by step, with each video building on the previous ideas.

(Videos continue below)

THE CIRCLE OF FIFTHS

HOW TO ACTUALLY UNDERSTAND THE CIRCLE OF 5THS

This lesson explains what the Circle of Fifths represents and why it appears so often in music theory. Rather than treating it as a chart to memorise, the focus is on understanding the relationships it shows between keys, sharps, flats, and harmony.

When the Circle of Fifths makes sense conceptually, it becomes a practical tool for recognising key signatures, chord movement, and common progressions.

As you watch, focus on the relationships between keys rather than trying to memorise the diagram itself.

CHORD CONSTRUCTION

HOW TO BUILD EVERY CHORD ON GUITAR

This lesson breaks down how chords are constructed by stacking intervals, starting from a root note. Instead of memorising chord shapes, it explains where chord qualities actually come from.

Understanding chord construction makes it much easier to learn new chords, modify existing shapes, and recognise why chords sound major, minor, diminished, or extended.

Pay attention to how each added interval changes the sound and function of the chord.

ARPEGGIOS

THE BEST WAY TO LEARN ARPEGGIOS ON GUITAR

(AND HOW TO USE THEM)

This lesson shows how arpeggios are directly connected to chord construction rather than being a separate concept. Arpeggios are presented as chords played one note at a time, not as isolated shapes to memorise.

When arpeggios are understood this way, they become a powerful tool for outlining harmony, improving fretboard awareness, and making solos sound more connected to the chords underneath.

Focus on how each arpeggio relates back to its parent chord and key.

CHORDS IN A MAJOR KEY

HOW TO FIND GUITAR CHORDS IN A MAJOR KEY

This lesson explains how chords are derived from the major scale and why certain chord qualities naturally occur within a major key. The goal is to understand the system behind chord progressions, not just memorise lists of chords.

Once this process is clear, it becomes much easier to build progressions, transpose ideas, and recognise common harmonic patterns across songs.

Watch how each chord is created from scale degrees and how they relate to the key centre.

CHORDS IN A MINOR KEY

HOW TO FIND GUITAR CHORDS IN A MINOR KEY

This lesson covers how chords are formed in a minor key and why minor harmony behaves differently from major. It clarifies where common minor-key chord qualities come from and how they function together.

Understanding this makes minor progressions easier to analyse, write, and improvise over without relying on guesswork.

Pay attention to how the key centre affects chord choices and harmonic movement.

INTERVALS

INTRODUCTION TO UNDERSTANDING INTERVALS ON GUITAR

This lesson introduces intervals as the distance between notes and explains why they are the foundation of all scales, chords, and harmony on the guitar. Rather than treating intervals as abstract labels, the focus is on hearing and recognising how they function musically.

When intervals are understood clearly, patterns across the fretboard stop feeling random and theory concepts begin to connect naturally. This makes it much easier to learn new material without starting from scratch each time.

As you watch, focus on how the same interval can appear in multiple locations and contexts on the fretboard.

A GUITARIST’S GUIDE TO SECONDARY DOMINANTS

WRITE BETTER CHORD PROGRESSIONS

This lesson explains what secondary dominants are and why they are used to temporarily create tension outside the home key. Instead of treating them as an advanced theory trick, the focus is on understanding their function and sound.

When secondary dominants are understood clearly, chord progressions become more flexible and expressive without losing their sense of direction.

Pay attention to how dominant chords naturally want to resolve and how this effect can be used deliberately in progressions.

HOW TO USE DIMINISHED CHORDS

DIMINISHED PASSING CHORDS

This lesson shows how diminished chords are commonly used as passing chords rather than static harmony. The emphasis is on understanding their movement and function instead of memorising isolated shapes.

Used this way, diminished chords become a practical tool for adding tension and smooth transitions between chords.

Focus on how diminished chords connect surrounding chords and create forward motion.

WHAT MAKES THIS CHORD SO USEFUL?

CHORD BUILDING MADE EASY

This lesson uses the major 7 chord as a template to demonstrate how most chords are constructed. By adjusting individual intervals within the chord (1–3–5–7), a wide range of chord types can be created logically.

Understanding chords this way removes the need to memorise endless shapes and makes unfamiliar chords easier to recognise and build.

As you watch, notice how changing a single interval alters the chord’s quality and function.

ALTERNATE GUITAR TUNINGS LESSON

EXPERIMENT WITH NEW GUITAR TUNINGS

This lesson provides an overview of some of the most commonly used alternate guitar tunings and where they tend to show up in real music. The examples focus on how different tunings change chord voicings, resonance, and the overall feel of the guitar.

By connecting each tuning to familiar songs, it becomes easier to hear why a particular tuning was chosen and what it makes possible musically.

As you watch, focus on how each tuning naturally suggests certain chord shapes and ideas.

THIS EASY PATTERN TELLS YOU EVERY CHORD IN EVERY KEY

This lesson introduces a simple fretboard pattern that can be used to determine the chords in any key. The goal is to reduce overthinking and provide a reliable method that works quickly in real playing situations.

When this pattern is understood, identifying diatonic chords becomes automatic and far less theoretical.

Focus on applying the pattern slowly at first, then using it in multiple keys to build confidence.