The same note will sound substantially different, depending on what string is used to play it. Sometimes the composer or arranger will specify the string to be used in order to achieve the desired tone quality; this is indicated in the music by the marking, for example, sul G, meaning to play on the G string. For example, playing very high up on the lower strings gives a distinctive quality to the sound. Otherwise, moving into different positions is usually done for ease of playing.

Bowing or plucking an open string—that is, a string played without any finger stopping it—gives a different sound from a stopped string, since the string vibrates more freely at the nut than under a finger. Other than the low G (which can be played in no other way), open strings are generally avoided in some styles of classical playing. This is because they have a somewhat harsher sound (especially open E) and it is not possible to directly use vibrato on an open string. However, this can be partially compensated by applying vibrato on a note that is an octave higher than the open string.