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The parts of a guitar visible from the outside make it look simple, overall, even though there are a few dozen parts that make it up. But the real complexity begins when the guitar is examined from the inside out.

The body of a guitar that gives the instrument its overall shape and basic tone is constructed from slabs of wood – the top and bottom – held together by ribs. In an acoustic guitar, the top typically has a large hole near the center. But inside, there’s more to the story.

Those pieces won’t be solid and rigid (necessary for structure, but for tone as well), unless they’re connected well. That basic adherence is achieved by glues developed over centuries of experimentation. Not only does the glue hold the pieces firmly, the type used also affects the tone.

Just as a Stradivarius violin is famous for its sound in part because of the coating or veneer used, so it is with a fine guitar. But that tone is affected not only by the external glaze, but also by the glue used to hold the pieces together.

Along with that basic bond from glue, there are a half-dozen bracing elements in a guitar that contribute to its structural strength and affect the tone. In electric guitars, and some acoustics, there’s often a truss rod down the middle of the neck to keep it rigid.

The tension on the strings can become great enough to warp or even break the neck or body. The truss helps prevent that, along with the basic hardness of the material used, usually wood.

But an acoustic guitar has much more. Inside the body at the interface between the top and ribs, and the ribs and bottom, there are liners and braces.

A liner is a curved piece lying along the ribs, often with routing grooves to give it extra rigidity. The braces are small, variously shaped pieces placed at pressure points (like the outermost part of a curve) that give the body even more strength.

Not only do those braces and liners protect the guitar from warping and breaking, like everything else on the instrument they affect the overall sound. They play a subsidiary role to the top and strings, of course. But, beyond the basic level, there are subtle factors that determine the final sound of any fine instrument. The liners and braces contribute to that sound.

Whether the hole in an acoustic guitar is considered inside or outside is a matter of perspective, since it sits at the boundary. But it, too, plays a part (though less than is commonly believed) in determining the guitar’s overall sound.

The strings vibrate the top (the soundboard), that vibration moves the air inside, and some of that is radiated out of the hole. But the shape and material lining the hole, like every other part, affects the final sound in complex ways.

A guitar is a harmonious whole, made so by the skill of the craftsmen who, over the centuries, have experimented endlessly to bring the final result to perfection. Modern materials have combined with ancient practice to make an instrument capable of producing lovely sound.