Guitar chords are built from groups of three notes called triads. Understanding how to use the major scale to build triads and recognizing the resultant sequence of major and minor chords are two extremely important aspects of music. You work with triads by stacking the major scale in 3rds.
Basics of the CAGED chord system
You can play literally thousands of different chord shapes on the fretboard, but most of them can be traced back to just five common open forms. These forms are C, A, G, E, and D. Together they make up what’s called the guitar CAGED chord system, which includes arpeggio patterns, chord inversions, and various chord voicings.
How to add chord tones and extensions
In addition to using plain major and minor chords, guitarists add other scale tones to triads to create chords like Cmaj7, Dm7, Gsus4, and Fadd9.
How to use passing chords
Other types of chords, called passing chords, don’t stem from the major scale at all. They sound very unusual on their own but create nice voice leading when placed in between the right chord changes.
How to chart chord progressions
You’ve probably heard musicians calling out numbers on the bandstand, right? “One . . .
four . . . five . . . ” — well, get ready to find out what those numbers mean. The numbers refer to the scale degrees and chords that the music cycles through.
Recognizing chord movement and playing by numbers can help you chart and remember songs better, which, in turn, enables you to apply scales properly, play by ear, and compose your own music.
Musicians often refer to a chord progression by the way it moves numerically through a scale or pattern rather than by its actual pitches. Fortunately, playing chord progressions and playing by numbers go hand in hand, and the whole concept is easier on the guitar than most other instruments. These chord patterns are the basis for most chord progressions used in popular music.