Playing

The standard way of holding the violin is with the left side of the jaw resting on the chinrest of the violin, and supported by the left shoulder, often assisted by a shoulder rest. This practice varies in some cultures; for instance, Indian (Carnatic and Hindustani) violinists play seated on the floor and rest the scroll of the instrument on the side of their foot. The strings may be sounded by drawing the hair of the bow across them (arco) or by plucking them (pizzicato). The left hand regulates the sounding length of the string by stopping it against the fingerboard with the fingertips, producing different pitches.

Left hand and pitch production

As the violin has no frets to stop the strings, the player must know exactly where to place the fingers on the strings to play with good intonation. Through practice and ear training, the violinist's left hand finds the notes intuitively by muscle memory. Beginners sometimes rely on tapes placed on the fingerboard for proper left hand finger placement, but usually abandon the tapes quickly as they advance. Another commonly-used marking technique uses dots of white-out on the fingerboard, which wear off in a few weeks of regular practice. This practice, unfortunately, is used sometimes in lieu of adequate ear-training, guiding the placement of fingers by eye and not by ear. Especially in the early stages of learning to play, the so-called "ringing tones" are useful. There are nine such notes in first position, where a stopped note sounds a unison or octave with another (open) string, causing it to vibrate sympathetically.
The fingers are conventionally numbered 1 (index) through 4 (little finger). Especially in instructional editions of violin music, numbers over the notes may indicate which finger to use, with "0" indicating "open" string. The chart to the right shows the arrangement of notes reachable in first position. Not shown on this chart is the way the spacing between note positions becomes closer as the fingers move up (in pitch) from the nut. The bars at the sides of the chart represent the usual possibilities for beginners' tape placements, at 1st, high 2nd, 3rd, and 4th fingers.

Positions

The placement of the left hand on the fingerboard is characterized by "positions". First position, where most beginners start (although some methods start in third position), is the most commonly used position in string music. The lowest note available in this position in standard tuning is an open G; the highest note in first position is played with the fourth finger on the E-string, sounding a B, or reaching up a half step (also known as the "extended fourth finger") to the C two octaves above middle C. Moving the hand up the neck, so the first finger takes the place of the second finger, brings the player into second position. Letting the first finger take the first-position place of the third finger brings the player to third position, and so on. The upper limit of the violin's range is largely determined by the skill of the player, who may easily play more than two octaves on a single string, and four octaves on the instrument as a whole, although when a violinist has progressed to the point of being able to use the entire range of the instrument, references to particular positions become less common. Position names are mostly used for the lower positions and in method books; for this reason, it is uncommon to hear references to anything higher than fifth position. The lowest position on a violin is half-position, where the first finger is a half-step away from the nut. This position is less frequently used. The highest position, practically speaking, is 15th position.
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.

Open strings

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.
In some cases playing an open string is called for by the composer (and explicitly marked in the music) for special effect, decided upon by the musician for artistic reasons (common in earlier works such as Bach), or played in a fast passage, where they usually cannot be distinguished.
Playing an open string simultaneously with a stopped note on an adjacent string produces a bagpipe-like drone, often used by composers in imitation of folk music. Sometimes the two notes are identical (for instance, playing a fingered A on the D string against the open A string), giving a ringing sort of "fiddling" sound. Playing an open string simultaneously with an identical stopped note can also be called for when more volume is required, especially in orchestral playing.

Double stops and drones

Double stopping is when two separate strings are stopped by the fingers, and bowed simultaneously, producing a sixth, third, fifth, etc. harmony. Sometimes moving to a higher position is necessary for the left hand to be able to reach both notes at once. Sounding an open string alongside a fingered note is another way to get a partial chord. While sometimes also called a double stop, it is more properly called a drone, as the drone note may be sustained for a passage of different notes played on the adjacent string. Three or four notes can also be played at one time (triple and quadruple stops, respectively), and, according to the style of music, the notes might all be played simultaneously or might be played as two successive double stops, favoring the higher notes. Playing the notes simultaneously is done by applying more pressure to the bow and/or bowing closer to the fingerboard.

Vibrato

Vibrato is a technique of the left hand and arm in which the pitch of a note varies in a pulsating rhythm. While various parts of the hand or arm may be involved in the motion, the end result is a movement of the fingertip bringing about a slight change in vibrating string length. Violinists oscillate backwards, or lower in pitch from the actual note when using vibrato, since perception favors the highest pitch in a varying sound.[14] Vibrato does little, if anything, to disguise an out-of-tune note: in other words, vibrato is a poor substitute for good intonation. Still, scales and other exercises meant to work on intonation are typically played without vibrato to make the work easier and more effective. Music students are taught that unless otherwise marked in music, vibrato is assumed or even mandatory. This can be an obstacle to a classically trained violinist wishing to play in a style that uses little or no vibrato at all, such as baroque music played in period style and many traditional fiddling styles.
Vibrato can be produced by a proper combination of finger, wrist and arm motions. One method, called "hand vibrato," involves rocking the hand back at the wrist to achieve oscillation, while another method, "arm vibrato," modulates the pitch by rocking at the elbow. A combination of these techniques allows a player to produce a large variety of tonal effects.

Vibrato Trill

Vibrato can also be used for a fast trill. A trill initiated from just hammering the finger up and down on the fingerboard will create a harsher quality than with a vibrato trill. For example, if trilling on the first finger, the second finger is placed very slightly off the string and vibrato is implemented. The second finger will lightly touch the string above the first finger causing the pitch to change. This has a softer quality and many think it is nicer-sounding than a hammered trill. Note - this trill technique only works well for semi-tonal trills, it is far more difficult to vibrato trill for an interval of a tone or more.