Armed with only three or four chords, the modern-day guitarist can play some of the greatest songs ever written. But, things used to be different--the guitar used to be ignored. And unlike other string instruments such as the violin--which has remained essentially unchanged for centuries--the guitar is always evolving.
When the guitar was in its infancy during the 16th century, it bore little resemblance to its modern-day incarnation. Early guitars were small and quiet and they stayed this way for 300 years. Because of their quiet volume, guitars were used more as a composing tool than as concert instruments. Imagine an 18th century composer with a guitar sitting by his bed. He dreams a glorious piece of music and wakes up in the middle of the night declaring, "I'll write the most beautiful melody in all of Vienna!" He lights a candle, grabs his guitar and works out the music before it leaves his head. Weeks later, the music gets played publicly to rave reviews. But of course, the music originally composed on the guitar has to be performed using louder instruments. In those days, there was no such thing as amplification--or even electricity for that matter. This meant that the quiet guitar was treated as the shy cousin of the instruments that were actually used in the orchestra.
The low volume problems with the guitar were due to a couple of factors: First, the guitars were as small as a frying pan. Second, the frets--the places on the neck of the guitar where the strings are pressed down to make notes--were made with tied pieces of "gut." Gut is basically sheep intestine which would be pretty soft. Strings were also commonly made with sheep innards, and even though sheep's intestines can be very long, string length was very short.
These problems kept the guitar relegated to composers' bedrooms until the beginning of the 19th century when advances in tooling allowed luthiers (instrument builders) to replace the gut frets with metal frets. Shortly thereafter, during the mid-19th century, a luthier named Antonio de Torres went to work on the volume problem. The first thing he did was make guitars bigger. Then he experimented with different types of woods, called "tone woods," to use on the top (the part with the hole in it) of the guitar. After finding some great tone woods, he then changed the bracing pattern on the inside of the guitar. Bracing is important because it keeps the thin top of the guitar from bending forward with the string tension. With better wood and better bracing, the volume of the guitar got louder. The "Stradivarius of the guitar," as Torres has been called, even went so far as to make a guitar with papier-mache back and sides, and a braced tone wood top to improve instrument volume. Torres is credited with inventing the modern-day classical guitar.
Around 1900, the guitar got another makeover, when the Martin Guitar Company, among others, began producing guitars with steel strings. The steel-string guitars had the interior bracing redesigned to support the extra tension put on the guitar top. And with this extra tension came even more volume. Voila--the modern-day steel string acoustic was born. Since then its sound has spread like bird flu in a chicken coop.
Shortly after the birth of the modern day steel string guitar, the devil got in on the action by trading Robert Johnson unparalleled blues-playing ability for his soul. Almost immediately after that, the first "air guitar" probably showed up.
Even with air guitars on the scene, volume continued to be a selective pressure in the evolution of the guitar. The next step in guitar construction involved some high voltage.
There has been some controversy surrounding the creation of the electric guitar. The basic rundown goes like this: A man named Les Paul discovered a way to electrify his guitar with a needle from an old gramophone. He eventually incorporated the use of a magnetic pickup with a solid body style guitar and made what is known as the modern-day Gibson Les Paul (Jimmy Page rocks one and so does Slash). Around the same time, a guy named Leo Fender came up with a slightly different design and called it the Broadcaster (that became the Telecaster--picture Bruce Springsteen in the "Born in the USA" video). Fender followed up this model with the Stratocaster (see Eric Clapton, Jimi Hendrix, et al.). What this means is: guitars got really loud. Loud enough to play "Purple Haze" and cause tinnitus.
This chain of events helped make the guitar one of the most dominant instruments in Western music over the last few decades and into the foreseeable future. When you go down to your local pub, you're more likely to hear a singer/ songwriter playing the guitar than the French horn. And there are reasons for this. The guitar can function as a rhythm or solo instrument; guitar chords have a full sound; and "Back in Black" doesn't sound good on the oboe. Above all, the guitar sounds cool.