Acoustic guitars produce their sound naturally using the vibration of the strings and resonance of the body to create sound in the air. The guitar top, or soundboard, is a finely crafted and engineered element often made of spruce, cedar, or mahogany. The back and sides are typically made from mahogany, sapele, rosewood, or maple. Some acoustic guitars have pickups and electronics in case you need to plug into an amp or PA to get more volume or want to add effects with pedals.
Acoustic Body Types
The most popular acoustic guitars are flat-tops. This traditional style is available in a number of sizes and body shapes ranging from tiny (Baby Taylor) to gargantuan (Gibson Super Jumbo). Obviously, the larger the guitar, the louder it is. Dreadnoughts like the ever-popular Martin D-28 are favorites of both flat-pickers and finger stylists on the basis of sheer volume and projection.
The smaller body sizes, variously called parlor, orchestra, and 000, make up in warmth and charm what they lack in sheer output. The Taylor Grand Concert and Grand Auditorium are popular choices in this size range. Think about what kind of venues you normally play, and consider the range of acoustic-electric pickup systems when deciding on the right guitar. As with every type of guitar, it's important to find the one that matches your personal musical voice.
There are still a handful of purely acoustic archtop guitars from various manufacturers, though they are very much a specialty item these days. But, if you're doing a solo jazz act or aspiring to be the next Freddie Green (Count Basie's long-time rhythm guitarist) they're worth checking out.