Teaching students how to locate the natural harmonics in the strings is extremely valuable as a way to introduce important markers on the instrument, the higher positions, as a vehicle to teach shifting and as a way to check for proper intonation. Harmonics are produced by lightly touching the string at certain nodes throughout. The easiest harmonic to produce is halfway between the bridge and the nut. Touching this harmonic will produce a pitch one octave higher than the open string.  

Moving the hand towards the nut or the bridge will produce more harmonics – There is a harmonic that divides the string into three equal parts and is a perfect 5th higher than the first harmonic, there is a harmonic that divides the string into four equal parts and is a perfect 4th higher than the second harmonic, and there is a harmonic that divides the string into five equal parts and is a Major 3rd higher than the third harmonic. On the D string, playing these harmonics while starting at the middle harmonic and moving towards the nut will produce the ascending pattern – D-A-D-F#. This same pattern can be played starting at the first harmonic and moving toward the bridge – D-A-D-F#. Additional higher harmonics are possible as shown in this video and are easier to produce when moving the left hand towards the bridge.  The double bass makes frequent use of harmonics in advanced solo playing.