Acoustic guitars remain as popular as ever, but what exactly is an acoustic guitar, and what makes it different to other popular guitars today? Very simply, it is the word acoustic which is significant in understanding what sets acoustic guitars apart from others. Almost every other kind of guitar available today relies upon some sort of external device being used in order to make the sound audible, or at least properly audible from a reasonable distance.

Since many guitars are played alongside other instruments - often quite noisy ones, it is usually necessary for these guitars to have devices attached to them to allow the sound to be heard, but it is not just the volume of the sound which is affected by these external devices. It is the actual sound, or voice, of the guitar which is affected, and there can be no one who could ever be in any doubt when listening to music, which is an electric guitar and which is not, since the sound style or voice is completely different. Electric guitars owe their distinctive voice not to the design of the guitar or the strings, or even the fret board, but to the combination of these factors and the external devices which give the instrument its fully formed voice. Acoustic guitars on the other hand are those that do not require or use any external devices, and can simply be picked up and played straight away.

They provide a far more natural, and often gentle tone, using the physical structure, design and properties of the guitar, and the material from which it is made, to give it its character and tone. The voice of an acoustic guitar is reliant entirely on the combination of the design, the actual materials used in its construction, and of course the person who is playing the instrument. The materials used in the construction of an acoustic guitar are of significance, since certain types of wood will be more elastic, and softer, which provides a dampening resonance to the sound, and the strings themselves will provide a particular tone and resonance of their own. Because there is a limit to the volume reasonably achieved using an acoustic guitar, often it is necessary when playing in a large hall, or with other instruments and musicians, to amplify the sound coming from the acoustic guitar as otherwise its sound would be lost. Simply trying to play harder or louder will only cause the voice to be stressed, and lose its character and tone.

Instead, external amplification devices are often used to increase the overall volume without affecting the tone and intricate characteristics of the instrument and the music being played. Acoustic guitars therefore may either be played on their own without any other devices attached, or with an amplification unit attached, but this in no way affects the style or tone of the guitar's voice, and therefore should not be confused with other styles of guitar which rely on these electronic devices entirely.

However, there are different types of acoustic guitar, and these provide quite contrasting voice styles. For example, there is the classical guitar, which is the most often considered, and the flamenco, which provides a very Mediterranean feel to the music, honouring the strong Spanish influence in the guitar's history. Additionally there are steel string guitars which use steel rather than nylon to provide a sharper, crisper sound to the individual notes played. Steel string guitars are most often found being used in traditional folk guitar music, or flat top styles. There are also twelve string guitars in the acoustic family, and one mustn't ignore the bass guitar, which whilst often seen in an electric form has an acoustic version too, although the tuning of these is very much more similar to that used in electric bass guitars.