The phrase "classical guitar" is ambiguous in that it might refer at least three different concepts:
- the instrumental technique — the individual strings are usually plucked with the fingernails or rarely without nails.
- its historic repertoire — though this is of lesser importance, since any repertoire can be (and is) played on the classical guitar (additionally: classical guitarists are known to borrow from the repertoires of a wide variety of instruments)
- its shape, construction and material — modern classical guitar shape, or historic classical guitar shapes (e.g. early romantic guitars from France and Italy). A guitar family tree can be identified. (The flamenco guitar is derived from the modern classical, but has differences in material, construction and sound)
The name classical guitar does not mean that only classical repertoire is performed on it, although classical music is a part of the instrument's core repertoire (due to the guitar's long history); instead all kinds of music (folk, jazz, flamenco, etc.) are performed on it.
The term modern classical guitar is sometimes used to distinguish the classical guitar from older forms of guitar, which are in their broadest sense also called classical, or more descriptively: early guitars. Examples of early guitars include the 6-string early romantic guitar (ca. 1790 - 1880), and the earlier baroque guitars with 5 courses.
Today's modern classical guitar is regarded as having been established from the late designs of the 19th century Spanish luthier Antonio Torres Jurado. Hence the modern classical guitar is sometimes called the "Spanish guitar".
The modern classical guitar is usually played in a seated position, with the instrument resting on the left lap - and the left foot placed on a footstool. Alternatively - if a footstool is not used - a guitar support can be placed between the guitar and the left lap (the support usually attaches to the instrument's side with suction cups). (There are of course exceptions, with some performers choosing to hold the instrument another way.)
Fingerings for both hands are often given in detail in classical guitar music notation. Fretting hand fingers are given as numbers in circles, plucking hand fingers are given as letters
When a fretting hand string is held over more than one string, that is called a barre chord. The notation for a barre is the Latin numeral for the fret in question.
Plucking of the string
Right-handed players use the fingers of the right hand to pluck the strings, with the thumb plucking from the top of a string downwards and the other fingers plucking from the bottom of string upwards. The little finger in classical technique as it evolved in the 20th century is used only to ride along with the ring finger without striking the strings and to thus physiologically facilitate the ring finger's motion. Some modern guitarists, such as Štěpán Rak, use the little finger independently, compensating for the little finger's shortness by maintaining an extremely long fingernail. In contrast, Flamenco technique, and classical compositions evoking Flamenco, employ the little finger semi-independently in the Flamenco four-finger rasgueado, that rapid strumming of the string by the fingers in reverse order employing the back of the fingernail—a familiar characteristic of Flamenco.
Direct contact with strings
As with other plucked instruments (such as the lute), the musician directly touches the strings (usually plucking) to produce the sound. This has important consequences: Different tone/timbre (of a single note) can be produced by plucking the string in different manners and in different positions.
To achieve tremolo effects and rapid, fluent scale passages, the player must practice alternation, that is, never plucking a string with the same finger twice in a row. Using p to indicate the thumb, i the index finger, m the middle finger and a the ring finger, common alternation patterns include:
- i-m-i-m Basic melody line on the treble strings. Has the appearance of "walking along the strings".
- i-m-a-i-m-a Tremolo pattern with a triplet feel (i.e. the same note is repeated three times).
- p-a-m-i-p-a-m-i Another tremolo pattern.
- p-m-p-m A way of playing a melody line on the lower strings.
Tone production/variation and freedom of performance
Guitarists have a lot of freedom within the mechanics of playing the instrument. Often these decisions with influence on tone/timbre - factors include:
- At what position along the string the finger plucks the string (This is actively changed by guitarists since it is an effective way of changing the sound(timbre) from "soft"(dolce) plucking the string near its middle, to "hard"(ponticelo) plucking the string near its end).
- Use of nail or not: today almost all concert guitarists use their fingernails (which must be smoothly filed and carefully shaped ) to pluck the string since it produces a sharper clearer sound, and also a better-controlled loud sound. The "use of nail or not" is usually a fixed consistent decision of the player and not varied; the thumb is an exception and might actively be varied between nail [sharper clearer sound] and flesh. Playing parameters include
- Which finger to use
- What angle of attack to hold the wrist and fingers at with respect to the strings
- Rest-stroke apoyando; the finger that plucks a string rests on the next string—traditionally used in single melody lines—versus free-stroke (tirando ( plucking the string without coming to a rest on the next string)
- Use of hammer-on and pull-off (Legato, slurs): This is where only the left hand is used in producing the sound. Since the string is usually already vibrating prior to applying the hammer-on or pull-off, the change of pitch is very smooth: it is hence used for articulation purposes and fast note progressions (since only a single hand is involved). The technique is often used in trills.
- Vibrato: Whilst a finger of the left-hand is pressing the string towards a fret, it can rapidly move the string slightly to and from (along the string), resulting in a slight but fast-changing increase and decrease in the string's tension and thus a proportional change in pitch - giving the impression of a fuller tone.
- One and the same note (in terms of pitch), can be played on many different strings (depending on the appropriate fret being used). Since the different strings have distinctive tones, the guitarist may choose to play on certain strings for particular tonal effects: The difference is greatest between the 3rd string (G - pure nylon) and the 4th string (D - nylon wound with thin metal). This, however also poses a difficulty in producing a uniform sound in melodic lines.
- Harmonics: The strings can be brought into different modes of vibration, where its overtones can be heard.
Since it is the hands and fingers that pluck the string and every person has different fingers, there are great differences in playing between guitarists; who often spend a lot of time finding their own way of playing that suits them best in terms of specific objectives: tone-production ("beauty"/quality of tone), minimum noise (e.g. clicking), large dynamic range (from soft to controlled loud), minimum (muscle) effort, fast "motion-recovery" (fast plucking when desired), healthy movement in fingers, wrist, hand and arm.
John Williams has remarked that since guitarists find it superficially very easy to play even things such as melody with accompaniment (e.g. Giuliani), [some guitarists'] "approach to tone production is also superficial, with little or no consideration given to voice matching and tonal contrasts".