Watch the Nonharmonic Tones online guitar lesson by Joe Dalton from Fretboard Epiphanies
Non-harmonic tones are notes that don’t belong to a particular chord. The notes in a D chord are D-F#-A. If we play a G on the first string with our pinky while holding the D chord at the second fret, we get a Dsus4 (D suspended 4th). The G note is four notes from the root (D-E-F#-G). The G is a non-harmonic tone. These are examples of non-harmonic tones. You can learn some of these as licks to throw into solos or as fills. Make certain you know what chord is at what fret. It is best to know where the root is.