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# Fret

For the acronym FRET in molecular biology, see Fluorescence resonance energy transfer.

A fret is a raised marker on the neck of a stringed instrument. Frets divide the neck into fixed segments at intervals related to a musical framework. For example, on instruments such as mandolins, each fret represents one semitone in the standard western system where one octave is divided into twelve semitones.

On most modern western instruments, frets are metal strips inserted into the fingerboard. On historical instruments and some non-European instruments, pieces of strings tied arround the neck serve as frets.

"To fret" is often used as a verb, meaning simply "to press down the string behind a fret."

Pressing the string against the neck reduces the vibrating length of the string to that between the bridge and the next fret between the fretting finger and the bridge, thus changing the pitch of the note produced. Thus the fret provides a sharp end to the vibrating part of the string. This is especially important for plucked instruments, since the tone would be muffled and have a short sustain if the string were stopped with the soft fingertip on a fretless fingerboard. Another advantage of frets is that they make it much easier to achieve an acceptable standard of intonation since the positions for the correct notes are given by the frets. Furthermore, playing chords works much better on a fretted fingerboard than on a unfretted one.

A disadvantage of using frets is that the player is restricted by the temperament given by the position of the frets. Some influence on the intonation is still possible, however. The string can be pulled to the side to increase the string tension and the pitch. This technique is sometimes used by rock and jazz guitarists and is a very important part of sitar playing. On instruments with thicker frets, the string tension and pitch will vary with the pressure of the finger behind the fret. Sometimes it is also possible pull the string toward the bridge or nut, thus lowering or raising the string tension and pitch, respectively. However, with the exception of instruments like the sitar, where extensive pulling of the string is possible, much less influence on the intonation is possible than on unfretted instruments.

Since the intonation of most modern western fretted instruments is equal tempered, the ratio of the distances of two consecutive frets to the bridge is $\sqrt[12]{2}$, whose numeric value is 1.059463. Theoretically, the twelfth fret should divide the string in two exact halves. In practice it is slightly closer to the nut to compensate for the increase in string tension when the string is pressed against the frets.

Slanted frets: Most frets are perpendicular to the instrument's neck. Though slanted frets would be more ergonomic, few luthiers offer slanted or fanned frets; Rickenbacker and Novax Guitars offer such guitars. (Note that slanted frets are available from Rickenbacker on only a few models and then only as an option. Rickenbacker's slanted frets models carry an SF after the model number (e.g. Rickenbacker 360/12 SF).

Fretlessness: Many fretted instruments are also available in fretless versions. For example, the bass guitar and acoustic bass guitar come in both varieties. The majority are fretted, like the vast majority of guitars, but a significant number of fretless basses are also played, in part drawing on the influence of the double bass (itself, virtually always fretless).

It is also possible to find semi-fretted instruments, although these are normally one-off, custom adaptations made for players who want to combine elements of both types of sound. One arrangement is for the frets to extend only part of the way along the neck so that the higher notes can be played with the smooth expression possible with a fretless fingerboard. Another approach is the use of frets that exend only partway across the fretboard so that some courses of strings are fretted and others fretless, for example Ryszard Latecki's Latar.

Another variant is called "scalloping" and involves the wood between some or all of the frets being scooped out. This allows a lighter touch for faster playing and also opens up new options for altering the pitch by bending the strings with the fretting hand. It had some popularity with musicians playing heavy metal music, although the ideas can also be seen in more ancient instruments such as the sitar.