Acoustic guitars are a descendant of one of the oldest families of stringed musical instruments: the lute. Classical and acoustic guitars are similar and often grouped into a single category; but some important differences exist between the two instruments. The most obvious difference is the type of strings used. Classical guitars commonly come outfitted with nylon or gut strings, which produce a warm sound. An acoustic guitar, on the other hand, uses steel strings that are similar to those used on electric guitars.
Steel strings produce a metallic sound and project better than nylon strings. Acoustic guitars also have a larger body and soundboard than do most classical guitars. The combination of steel strings and a larger body further provides the acoustic guitar with greater sound projection and makes an acoustic guitar easier to hear when played alongside other acoustic instruments.