Notes:

• The word, "harmonic," was borrowed from music by the field of physics, where it describes how waves of many kinds (light, water, etc.), can be divided into many fractions.

• When guitar players talk about harmonics, they simply mean the "bell-like" tones you can get by touching gently on a string to make it vibrate in half, thirds, fourths, etc.

• The words, "harmonic" and "overtone" are sometimes used interchangeably. Technically speaking, they are a little different. In physics, the open string is called the "first harmonic," and stopping the string at the 12th fret creates the "second harmonic." In overtone terminology, the open string is called the "fundamental," and stopping the string at the 12th fret is the "first overtone."

• If you look at a frequency analysis of a note played on a guitar string, you can see the fundamental frequency (for example, open A string is 110 cycles per second), plus many overtones that are multiples of that (220, 330, 440, etc.). These built-in overtones give each instrument its essential character.

• Just barely touch the string (usually directly over a fret), to make a "harmonic." Pick quite close to the bridge to get the clearest sound. Pull your finger away right after you pick.

• The "harmonic series" means what scale tone results from playing the harmonics in order: 12th fret (root), 7th fret: (fifth of scale), 5th fret (root), 4th fret (third). The next two harmonics are not directly over a fret. Touching at approximately fret location 3.2 results in another 5th, and touching at about 2.8 results in a b7! (For theory geeks, this seems to mean the Dominant 7th chord is a fundamental part of physical reality!)

• Touching the D, G and B strings at 12th fret makes a G chord in harmonics. Making harmonics on the same strings at the 7th fret makes a D chord!

• Artificial Harmonic: Making a harmonic with picking hand 12 frets above where you're fretting. You can do this with chords or single note licks. Most players touch over the fret with first finger and pick with the thumb.

• Pinch Harmonic: Touch the string with the edge of the thumb of your picking hand immediately after picking the string. This is not an exact science--you just have to experiment by moving your picking hand along the string to find where the harmonics "pop out." Using a distortion or overdrive pedal can make them pop out more easily.

• Check out the other vid's in this series on Expressive Techniques.