Basic Info
It isn't widely known (even by guitarists) but the guitar is actually a transposing instrument! It's still written in the key of C but every note is written one octave higher than it sounds; since there is no bass clef being used this helps keep everything as close to the middle of the treble clef as possible.
This is especially important to keep in mind when writing unison lines or arranging between the guitar, bass guitar and piano/keys.
Types
Electric Guitar
The electric guitar is the most common type of guitar in a jazz big band along with most other contemporary, rock and funk ensembles. Although there are many different designs and types of the instrument all electric guitars have similar ranges, articulations and effects.
Acoustic Guitar
The acoustic guitar is not a common instrument in most jazz, rock or funk ensembles but you will occasionally see it either as a rhythm instrument on its own or supporting an electric lead guitar. The essentials of the instrument are the same as the electric but the range and certain effects are slightly limited (See the range and effects sections for more information).
Baritone Guitar
A rare version of the guitar for most groups but becoming more common in rock and heavy music. The baritone guitar has a longer scale (neck length) and much thicker strings than a standard acoustic or electric guitar and can therefore be tuned lower without sacrificing string tension or note intonation.
Range
Electric Guitar
Regular Range
In normal tuning the guitar can play an E2 as its lowest note although remember that this note is written as an E3 in the treble clef (the guitar is written an octave higher than it sounds). A typical electric or jazz hollow-body guitar will usually have a minimum of 21 frets and a maximum of 24; with 24 frets the player will have access to two octaves per string). It is usually safe to write a D7 but anything higher should be checked with the player/instrument.
Extended Range
A normal electric guitar can have its lowest E string (written E3) tuned down a step to a D (written D3) without much trouble. Depending on the instrument's quality and set up a written C#3 or even a low C3 is sometimes possible but as a general rule D is the lowest note that can safely be down-tuned. Any lower than that and a baritone or 7 string guitar should be used (see below). Many electric guitars also have 24 frets allowing for a high E7.
Acoustic Guitar
Regular Range
The acoustic guitar has the same low range as the electric (including the down-tuning) but is usually not able to hit as high of a register; this is due mainly to the body shape and design of MOST acoustic guitars. A high written G6 is the highest comfortably playable note on most acoustic guitars although on some nylon/classical guitars this can be a bit of a reach (E6 being the highest comfortable note in that case).
Baritone Guitar
Regular Range
The baritone guitar has a longer scale and much thicker strings than a standard guitar, this allows it to be tuned a fourth lower without sacrificing string tension and pitch intonation. A few standard tunings exist for baritone but typically it will be tuned to a low B (B2 concert) or C (C3 concert); most baritone guitars can be tuned as low as A2 concert without issue or even as high as D (D3 concert) in some cases. Like the electric guitar some baritones have a 24th fret and can reach a high B7 (sounds like B6).
Articulations
Articulations
Staccato
On the guitar a staccato is played usually by lifting the fret hand finger up early, cutting off the length of the note. This can be done any number of times in a row; legato markings should be used for notes in a staccato passage that need to be played for their full value (see below).
Tenuto
Tenuto markings on the guitar are best used when a note surrounded by staccato markings needs to be played for its full value. On its own this marking denotes that the note should receive some emphasis although what form that will take is contextual and may be left up to the player (unless specified otherwise).
Accent
Accenting a note on the guitar is achieved usually by picking the desired note harder than usual. Can be used on both full chords and single notes.
Marcato
As with jazz arranging in general the marcato articulation usually results in an accented note with a shorter value (about 2/3) than a standard accent. Use for short, punchy lines or chord shots that need some space and tightness to them.
Slur/Legato
A slur on the guitar can be played in a number of ways: a hammer-on/pull-off (most common), a slide or a bend (less common). Using a slur articulation without specifying which technique to use will leave the player to decide which is best to use in the context of the song/phrase. Entire slurred phrases on the guitar can also be notated with a legato marking although a slur should still be used. See below for more information on each separate technique.
Hammer-On
A hammer-on is achieved by using the fret hand to "hammer" onto the neck of the guitar, producing the desired note. Because this note is not being picked by the other hand its volume is slightly lower than that of a picked note with each successive hammer-on being slightly quieter than the previous note. Long passages of hammer-ons are almost always played by incorporating pull-offs into the playing as well (see below).
Pull-Off
The opposite of a hammer-on, the pull-off is achieved by picking a note then "pulling off" the finger either to an open string to to another fretted note below. Long passages involving either hammer-ons or pull-offs typically incorporate both techniques to keep the volume and rhythm consistent. In a nutshell: a hammer-on is for ascending movement and a pull-off is for descending passages but expect some combination of both if the passage is longer than one or two notes.
Effects
Special Effects
String Bend
A common guitar effect where the string is pushed up or down to increase its pitch. Bends should be notated either by using a grace note if the note is bent immediately or using normal bend notation if the bend is in time. The first note of the bend should be the actual note being played with the second note being what is being bent up to; typically a whole step bend is the recommended maximum although a minor 3rd bend can also be possible in the higher register.
Slide
A slide is a common guitar articulation/effect that involves picking a note (or group of notes) and physically sliding the fret hand finger up or down towards the next note. As mentioned above a written slur might result in a side in certain contexts but to specify one the standard slide notation can be used.
Vibrato
Vibrato on the guitar is achieved by moving/bending the fret hand finger up and down slightly to create subtle pitch fluctuations in the held note. This can be done slowly or quickly for varying different types of vibrato; this effect should be notated either with a vibrato marking or with a vibrato expression in the case where another articulation is already being used.
Trill
A trill on the guitar is accomplished by rapidly hammering-on and pulling-off between two notes in rapid succession. Unlike some other instruments a trill can be played as high as a major third without too much difficulty. Usually by default the trill will either be a whole step or the next logical note (next note in the key or altered note in the bar), accidentals can also be placed above the trill marking to specify which note is to be played.
Fret-Hand Mute
There a few possible types of mutes on the guitar but the most common in jazz and contemporary music is the fret-hand mute (sometimes called the left-hand mute but this is inaccurate as not all guitar players are right-handed). This effect is achieved by preventing the strings from producing a tone with the fret-hand and striking one or more strings with the pick hand producing the mute effect. Most common in funk rhythm playing but also seen in rock and jazz as well.
Natural Harmonics
The guitar is able to produce natural harmonics like most other stringed instruments. The notated pitch should be the pitch struck and not necessarily the resulting harmonic produced. There are a couple ways of notating this: one is by using a diamond notehead shape (first in the example) and the second is a diamond articulation above a normal notehead (less common these days). Finale likes to use the articulation instead of the notehead but most guitar players are more used to the former way at least in contemporary music.
Tremolo Picking
Tremolo picking is an effect unique to the guitar and other instruments played with a pick, commonly heard in rock, surf and heavier forms of music. This technique is best used on held notes and can be used to play extremely fast passages but arpeggios and intricate single lines can be awkward and are not recommended.