Col legno is Italian for "with the wood." It is a technique that emits a wooden crackling sound from the cello. The cellist performs this technique by bowing the strings with the back, wooden side of the bow instead of using the hairs. Composers will write "col legno" at the point that this technique should occur within the music. This technique commonly appears in film scores to create a spooky, eerie effect.
Vibrato appears in many cello pieces. However, in modern works, it may create special effects. The typically cello vibrato is quick and has a thin texture. In modern cello works, it is sometimes requires that the cellist create a wide and expansive vibrato that is similar to a tremolo on a single note. This technique creates a striking, sometimes humorous and obscured pitch.
Harmonics create thin, pale and ghostly pitches played in the high register of the cello. By dividing the string with a finger, the cellist can shorten and double the intensity of the vibrating string. This creates pitches that are proportional to the strings division. Dividing the string in half will create a pitch an octave higher, while dividing the string into thirds will create a pitch a fifth and an octave higher. There are several ways to divide the string to create numerous harmonics.
The cello is capable of playing double, triple and quadruple stops. Double stops will allow two pitches to sound simultaneously, provided the pitches are on adjacent strings. Triple and Quadruple stops require that the cellist divide the chord into two groups since the nature of the cello bow will only let the cellist play two strings at a time. Earlier cello bows curved, allowing the cellist to play complete chords; however, these bows made it difficult to play fast passages, so the bow design changed to an inverted bow.