The guitar is one of the most versatile musical instruments you could ever play. It can produce a wide range of sounds, depending on the make, model, type of wood, strings, pickups, amps and a whole host of other factors. Guitarists choose their instruments carefully, until they find the one that produces the desired sound.
The acoustic guitar is primarily used in folk, blues, rock and country music, but it can be heard in several other genres as well. It produces its sound without the help of an amplifier, using the vibration of its strings and hollow body instead. The size of an acoustic helps determine the sound it produces – larger bodies, such as jumbos and dreadnaughts, produce louder sounds. The wood used to construct the guitar can also make a huge tonal difference. For example, a mahogany body will produce a softer, warmer tone than a guitar made from ash or alder. Strings are also important; a heavier string gauge will produce a thicker tone.
The electric guitar needs an amp to produce its sound. It's slimmer than an acoustic and is easier to hold and play, but it weighs more because of its solid body. Sound is produced in a similar manner to the acoustic, in that it's made by the vibration of the strings. But instead of the sound resonating through a hollow body, the vibrations are detected by pickups, which transmit the sound through the cord and out of the amplifier. The same rules regarding wood and strings for the acoustic apply to the electric, but the pickups make a big difference in the way an electric sounds. It all depends on what you want to play. If you want a softer, more delicate sound, get pickups that can produce it; if you're a metalhead, get pickups that will make your guitar scream.
A bass guitar is one that uses thicker strings to produce a much lower sound. Bass guitars help round out the sound of a band, providing that very important but often overlooked low end. There are typically fewer strings on a bass than on a guitar (four and six strings, respectively), but there are variations, of course. Five-, six- and even seven-string basses are available. The bass guitar is often overshadowed by the regular guitar; the spotlight always seems to be on the guitar player rather than the bassist. But some bands and genres feature their bassists prominently, such as the Red Hot Chili Peppers (Flea), Primus (Les Claypool), and Bootsy Collins.
There are many ways to learn how to play guitar. You can make some progress with instructional books and CDs, but the best way is from one-on-one guitar lessons with a guitar teacher. A good teacher will let you learn at your own pace, and will provide a mix of practical and theory. They will also teach you the songs you want to play, as well as giving you the standard exercises. They should tailor their teaching around what you want to learn. But ultimately it comes down to you and your willingness to practice. Practice is absolutely vital to improving as a guitarist.
Guitar music, that is, guitar sheet music, is written in two different forms: musical notation and guitar tablature. Musical notation uses proper music notes to mark what note is played and for how long. Unless you know how to read music, you likely won't be able to make sense of notation. This is where tablature (tabs for short) comes in. Guitar tabs use numbers to mark the fret and string in which a note is played on the fretboard, but it doesn't tell you how long the note is sustained; you need to figure that out by ear. You can find books with notation and tabs in music stores, bookstores or online. In fact, the Internet is a great place to find free guitar tabs.