Guitars fall into two broad groups: acoustic and electric. Within the acoustic category are classical, flamenco and steel-string instruments. The electric types include leads and basses. Some models are a hybrid of acoustics and electrics, having the sound and basic design of the first group but being outfitted with parts that amplify the sound when desired. Certain kinds work better for particular genres of music than others, so many players choose instruments based on the style they want to play or effects they want to get.
Acoustics
Acoustic guitars rely on a soundboard to convert and amplify the energy of vibrating strings. Originating from instruments in Asia, they have been around in various designs for hundreds of years and don't require any electricity to get a good sound. They usually have a hollow body and are made of various types of wood.
Classical
A major subgroup of this category is classical guitars, which usually have a warm, full-bodied sound. The key element of these instruments is that they use nylon strings rather than metal. The wideness and flat construction of the neck make it very easy to play the chords, scales and arpeggios classical music requires, although it can be troublesome for people with shorter fingers. Players usually make a sound by plucking the strings, but in some styles of music, strumming is also required. Some types have additional strings and, therefore, are known as "extended-range."
These instruments usually have a beautifully mellow sound, so they work well in more intimate settings and blend well. Outside of classical music, they are a favorite of folk musicians. Willie Nelson, a country artist whose career spans several decades, is a famous musician who uses one.
Flamenco
Flamenco guitars are similar to their classical cousins, but they are made a little differently. Although they use nylon strings, they typically are lighter, having a body usually made of cypress and a top of spruce. Sometimes harder woods like rosewood are used when a person wants an instrument that is a little louder. These versions also are outfitted with golpeadores, or tapping plates, which players hit with their fingers to make rhythmic, percussive sounds characteristic of the flamenco style. They have a quicker response and brighter sound than the classical versions, as well, which works to produce crisp playing that carries.
Steel-String
Steel-stringed instruments, sometimes called flat-tops, are different than nylon-string versions in that the string tension is greater, putting more pressure on the bridge and soundboard. In general, manufacturers design the instruments with this additional stress in mind and don't recommend putting steel strings on classical models. The construction of the strings generally makes tuning more stable, however, and the neck is a little narrower. They come in 6- and 12-string types.
Archtops are a subgroup of steel-string instruments in which the front — and sometimes the back — of the instrument is rounded, more like a violin or mandolin. These guitars also usually feature F-holes in the belly. Generally, their more rounded design gives them a rich, loud sound. They are popular in jazz and country music. Many manufacturers are making archtops that are acoustic-electric, but some are still purely acoustic.
Although factors such as wood choice and body shape affect overall sound, the tone of steel-string is often crisper and brighter than classical instruments, making them better for genres like rock, pop or country. Elvis Presley gyrated his way to fame with an acoustic steel-stringed guitar in hand, followed by 1960s performers and groups such as The Mamas and the Papas, Arlo Guthrie, Joan Baez, Bob Dylan, Simon & Garfunkel and Donovan. They also have been featured by famous rock legends like Crosby, Stills, Nash & Young, Jethro Tull, and more recently, Dave Matthews, Sheryl Crow, The Indigo Girls and Melissa Etheridge.
Acoustic Bass
Acoustic basses usually have four strings are tuned the same way as electric basses: E, A, D, G, one octave down from the lowest four strings on a 6-string. They typically feature a wide body and have a warmer, full, mellow sound. People use them for accompaniment in ballads, certain types of fusion music and in jazz, although a stand-up bass is more common. A working bassist might keep one as a secondary instrument for use in certain songs within his or her band’s repertoire. A special kind of acoustic bass is the 6-string guitarrón, which is used in mariachi bands.
Electrics
Unlike acoustics, electrics require an amplifier to produce a good sound. Companies first started making them in the 1930s when genres like jazz and swing were very popular. Originally, they had semi-hollow bodies for a well-rounded, warmer tone, but eventually, guitar makers figured out that solid construction typically worked better overall for the types of music people wanted them for.
Standard (Lead) Electrics
A standard electric typically takes the melody or lead in a band. Like an acoustic, it usually has six strings. A big difference that often helps beginners, however, is that the strings of an electric typically are closer to the frets and are a lighter gauge, simply because the amplifier does most of the work to produce the sound. Players don't have to press down nearly as hard when practicing or performing because of this, yet they still can get a sound that is very clean.
One of the hallmarks of these instruments is that, because of the way the sound is amplified, players can create special effects if desired. They can make the guitar seem to "scream," for example, or they can use tools like whammy boards and foot pedals to produce sounds like vibrato, pitch bends, echos and more. An example of a work that has become famous for these types of effects is Peter Frampton's Do You Feel Like We Do, which uses a talk box to mimic human speech.
Electrics shot to fame with the help of pioneers like Chuck Berry and anthems like his own Johnny B. Goode. The ripping, irresistible licks and hooks of the instrument booted the 1960s folk scene out the door and ushered in the age of rock 'n' roll. The Beatles, Rolling Stones, Eric Clapton’s Cream, Jimi Hendrix and Janis Joplin’s Big Brother & The Holding Company were just a handful of bands that epitomized the wide-ranging sound and appeal of electric guitars. Today, people use electrics in many genres, including metal, funk, R&B, hip-hop, rap, disco and blues.
Electric Bass
Electric basses provide the heart-pumping, chest-thumping drive of genres like rock, dance, techno, funk, hip-hop and rap music. Picked, plucked or slapped, these guitars pound out the low notes that give songs a strong foundation. Less frequently, people play them more like leads, particularly in jazz. Two good examples are Victor Bailey's version of Birdland by Weather Report and Stuart Hamm's Country Music (A Night in Hell).
Acoustic-Electrics
These instruments provide the best of both the acoustic and electric worlds. They have transducers, microphones or pickups to make their sound louder. They do not necessarily have to be plugged in to sound good, however. Most people who use these want the sound of an acoustic but need good volume, such as if they are performing for a lot of people. Like classical guitars, they are used mainly for classical and folk music, but because they can be connected to the same tools electric guitarists use, players have a lot more flexibility in terms of the effects and styles they can explore.