In recent years, there has been a respectable surge in the popularity of "unplugged" performances. Such exhibitions, as one might assume from the name, feature artists in small venues performing acoustically for small audiences. One interesting aspect to these performances is that sometimes the artists perform on electric guitars without using amplifiers. The irony, of course, is that electric guitars were specifically designed to be able to use amplifiers so that the music could be heard.

We appear to have come full circle. An unplugged performance, I would hypothesize, is an attempt by both the artist and the audient to "get back to the music." And there's certainly nothing wrong with that. But the reason both the venue and the audience are small is that if they were not, no one would be able to hear anything. The fact remains that electric guitars are designed to be used with amplifiers. If they're not, it is very difficult to hear what is being played because (most) electric guitar bodies are solid, rather than hollow like that of an acoustic instrument. So while unplugged performances may have artistic merit, they fail to make use of one of the electric guitar's most potent and important assets: the amplifier.

A guitar amplifier is simply an electronic amplifier designed for use with an electric guitar. An electronic amplifier, in turn, is a device designed to increase the power and amplitude of a signal. In this case, that signal is received from the guitar. Guitar amplifiers have been around since the early 1930s. At that time and through the 1940s, Hawaiian music was all the rage and amplifiers were used primarily with the lap steel guitar Hawaiian guitar. Then in the mid-1950s, thanks to the rock and roll revolution, the electric guitar took off and so did its amplifiers. Old black and white American Bandstand episodes show artists performing on stages that are subtly edged with the amplifiers attached to the electric guitars. But it didn't stop there. During the next decade, the artists began to experiment with distortion that could be caused by deliberately overloading their amplifiers. This eventually led to the incorporation of preamplifier distortion controls, which almost qualify guitar amplifiers as musical instruments in their own rights. Certainly it has become impossible to imagine modern music without the use of these devices.

Today, most guitar amps come in two general types. The first is the combination, or "combo," amplifier, which contains the amplifier head and guitar speakers in a single unit. The amplifier head contains the electronic circuitry constituting the preamp, built-in effects processing and power amplifier. The other type of amplifier is comprised of two separate speakers joined by cables. In this form, the amplifier head is housed in one unit while the guitar speakers are in the other. The unit with the head is commonly placed on top of one or more guitar speakers.

Among the two general types of amps, there are a number of different subcategories favored by different genres and instruments. Traditional amps, known for their clean, warm sound, are often used by rock, blues, country, indie and alternative bands. Hard rock-style amps, as the name intimates, are used by hard rock, metal and punk artists and often include a number of distortion effects and preamp controls. Bass amps boast extended bass response and tone controls that optimize a bass's sound. Finally acoustics amps, an apparent contradiction in terms, are designed to be used with acoustic instruments that have built-in pickups or microphones.