This is an overview of the methods by which the neck of a guitar is attached to the body. The three main methods are bolt-on, set-in (glued), and neck-through-body. They each have different construction expense and tonal qualities. It should be noted that bolt-on and neck-through-body are not used on acoustic guitars¹, only electric.

Something That Should Be Noted

It is commonly believed that the body of an electric guitar is completely inert; however, this is not strictly true. Even though it's electric, the sound is still produced by mechanical factors. Factors like sustain and tone are properties of the string and so are influenced by the rigidity of the parts of the instrument that run between the nut² and the bridge³.

Bolt-on

The bolt-on⁴ neck is the cheapest method by which a guitar neck can be attached and is generally associated with Fender (the brand that popularised it). The body of a guitar with a bolt-on neck generally is channelled to accommodate the neck. The neck is then put into this channel and is screwed into place. The bolts are almost never attached directly to the wood as this would cause the wood to crack. Instead, a metal plate is put between the body and the bolts, reducing the pressure on the wood. While this plate is sometimes hidden, more traditionally it sticks out from the wood. This causes one of the major issues with the bolt-on neck (see below).

Advantages and Disadvantages

The greatest advantages of the bolt-on neck are that it is cheap to manufacture, easier to mass produce, and it makes replacing the neck easy. If the neck is broken on a bolt-on, all that has to be done is to de-string it, unbolt it, remove the neck, put on replacement neck, bolt on the replacement, and restring it. It is not this simple on other neck types⁵. Another advantage (to certain players) is that it provides a brighter tone than the other methods. It can also allow for the neck-to-body angle to be adjusted.

The disadvantages of the bolt-on neck are many. The neck plate restricts access to the upper frets, unless it is hidden. The method inherently creates a poor contact between the neck and the body, resulting in low sustain⁶.

Set-in

The set-in neck is a more expensive method and provides good tonal qualities. This method is most commonly associated with acoustic guitars and Gibson electrics. In this method, the neck is placed in a channel (similar to the one found in a bolt-on construction) bound to the body via an adhesive.

Advantages and Disadvantages

One of the advantages of the set-in neck is that it is easier to play the upper frets. It creates a stronger neck connection than a bolt-on neck. It also produces a warmer tone with more sustain.

The disadvantages are that they are more expensive to manufacture and are much more expensive to repair than a bolt-on neck, should something happen to the neck. Also, while the neck connection is stronger, it is also more brittle.

Neck-through-body

The neck-through-body (or through-body) method is the most expensive method, but provides excellent tonal qualities. This is most often used by high-end manufacturers such as Rickenbacker and Alembic. In a through-body construction, the neck is a single piece of wood (or multiple layers of wood in the case of laminate construction) that runs the whole length of the body. The rest of the body are 'wings' that are attached to the neck. Since the neck runs the whole length of the body, the vibration of the string is carried on a single part of the guitar.

Advantages and Disadvantages

One of the advantages is that there is no heel created from the neck joint, resulting in very easy access to the upper frets. It creates a neck connection that is stronger than any of the other methods. It also provides immense sustain and great tone.

The disadvantages are that it is very expensive, difficult to mass produce, and it is essentially impossible to repair the neck. Also, as all the tension from the strings is acting on the neck, it is more prone to warping. As such, many instruments use two truss rods instead of one to help further reinforce the neck⁷.