When one speaks of "the strings" of the orchestra, it customarily refers to the instruments of the violin family. There are four different instruments, the highest being the violins, then the violas, then cellos, and finally basses (also called string basses, double basses, or contrabasses). Unlike all the other sections of the orchestra, the strings typically have many instruments playing a single part (the violins are traditionally divided into two parts, and the basses most often play the same part as the cellos, but one octave lower). This not only allows the quieter strings to balance the instruments of the wind section in loudness, but also affects the timbre. The sound of the strings playing together is one of the most common timbres of orchestral scores.
While the instruments of the violin family are usually bowed, they can also be plucked, a technique known as pizzicato.
Another technique is to move the bow back and forth as quickly as possible, a technique known as unmeasured tremolo:
By lightly touching the string at certain points, players can also play extremely high, glassy notes called harmonics:
In the following clip, an unearthly atmosphere is created with a combination of tremolo harmonics, pizzicato, sliding pitch (portamento) and hitting the strings with the wood of the bow, a technique called col legno:
