The fascination of the guitar reached the peak of its popularity thanks to the advent of the electical vesion. Its evolution, like that of the acoustic instrument, took place in the USA. Fundamentally, one characteristic common only to electric guitars is the pick-up. This is the heart of the instrument, at least in the enhancement phase of the sound. In fact, the pick-up has the job of converting the vibration from the strings into electrical signal, which is then processed by the amplifier and reconverted into physical sound.
There are two main versions of the electric guitar: the solid-body and the hollow-body.
Historically, the solid-body guitar is the derivation of the acoustic guitar (in the 1920's and 30's) where the first models of pick-ups were mounted. The requirements of this era was the need for more volume from the guitar, especially in orchestra's with many elements where the sound of the acoustic guitar was suffocated by the volume of the other instruments. The problem was in the fact that the top panel where the pick-ups were mounted was not very stable and moved with the vibration of the strings, or triggered an audio effect called feedback. In the solid-body electical guitar, the mass of the body is so high that it drastically reduces the capacity to transmit the vibrations. You ask if this is something good: it's clear that wood must vibrate, in fact a good solid-body can maintain a good dose of harmonic vibration, avoiding the instability typical of an acoustic instrument, that, as we have seen, can be amplified in many other ways.
Another characteristic of the solid-body is surely the fact that it can assume particular shapes, something thats practically impossible to do with an acoustic guitar, due to certain design criteria needed to have a good tone response.
The wood used in the construction of a solid-body must be very hard, oven dried or seasoned; for example, excellent woods are mahogany, alder, maple, ash and walnut. In the last few years, alternative materials have also been used to make the body, such as carbon fiber, metal, and even glass (however, not always with satisfying results). You need to consider the fact that the construction material of the body, either hollow or solid, always has an effect on the sound yield of the instrument. Furthermore, the neck can be made of other materials, like the graphite of the Steimberger guitars, and can also effect the sound of the instrument.

Analysis of the electic guitar

We will now analyze the parts that make up a common electrical guitar.
In the figure you can see the more important elements of a solid-body guitar. The model shown here is probably the most famous electric guitar ever made, which is the Fender Stratocaster, in the 1990 version called American Standard.

Practically all the parts that distinguish the solid-body electric from the acoustic guitar are found on the body of the instrument. The necks are also different, but the methodology remains the same. Lets look at the parts of the body, starting with the body itself.

The body

As previously stated, the body of the electric guitar is fundamental both from an aesthetic and tonal point of view. It has all the parts that allows the instrument to comunicate sound information with the amplification, which are the pick-ups, the tone and volume controls, the pick-up selector and the output jack.
Normally the body is composed of one block of wood, on which all necessary cuts are made for the various parts, such as the lodging of the pick-ups and the electronic circuits. It is then painted to its final color.
Another type of body is made of two parts. A thin top panel is placed over the lower portion, usually of different woods.
Another kind of body can be formed by two lateral pieces combined to a central section which is the neck of the instrument.
These are the three main construction philosophies, where the first two are very common in solid-body guitars.
A very important characteristic comes from the fact that the body has one or two shoulders, in the figure shown as the upper and lower. The lower shoulder helps access the higher areas of the fretboard. In fact, the fretboard of the electric guitar is used in its scale, depending of the number of frets, as we will see later.

The neck

The basic construction techniques of the neck is no different than that already seen for the neck of the acoustic guitar. The difference is mainly in the fact that you can play past the 12th fret. This therefore requires easy accessibility to the higher areas of the fretboard, with the use of the shoulder. The fretboard is longer than that of a folk guitar, and in fact can have 21, 22 or 24 frets, all accessible.
Furthermore, having much smaller and softer strings with respect to the acoustic guitar, the electric guitar is smaller in size, even if the shapes change with the different models.
The headstock can have many different forms. Normally there are three independant tuning pegs per side, or there can be the Fender type system that has all six pegs on one side. The tuning pegs are always independent from each other, using the same system seen for the folk guitar.

As you can see in the figure above, there are practically two methods for joining the neck to the body, which are glued and bolted. Today there are two opposite alliances as to which is the best system of joining the neck to the body. On one side we have the supporters of the jointed and glued neck, which gives a better sustain to the vibration of the strings, thanks to the fact that the joint becomes one piece with the body, like with the acoustic guitar. The others instead maintain that a bolted neck is a guarantee of stability, admitting that a little sustain is lost. In the middle, we can say that both systems are valid, because in the end, all the other materials that the guitar is made of also count, therefore becoming a very personal choice.
We will conclude by breifly talking about the reinforcing bar of the neck, or trusrod, whose technical characteristics we have already seen in the acoustic section. The regulation of the trusrod could cause problems with the frequent use, and with a lot of energy, of the tremolo bar. This is another reason why its important to have the correct tension of the neck. If you are unsure of how to regulate the neck, my suggestion is to let an expert do it. You will save time, money and...