As you likely learned in school, a guitar falls into the classification of a string instrument because it produces its sound through the vibrations of taut strings that are either plucked or strummed.
There are three different types of guitars: electric, acoustic and classical.
Classical Guitar
Also known as the “Spanish guitar,” the classical guitar is the most commonly available and purchased guitar today. It has a hollow body and six nylon or – less frequently – steel stings. The sound is produced by the vibrations of the strings reverberating and being resonated through a built-in hole in the body.
Because classical guitars generally have stings made of nylon rather than steel, they tend to be easier to pluck/strum than other guitars, and can be played using your fingers rather than a pick. Classical guitars are also typically used without amplifiers and can play Latin, Flamenco and classical music.
Acoustic Guitar
An acoustic guitar is visibly similar to a classical guitar; likewise, similarly to a classical guitar, an acoustic guitar is normally played without the use of amplifiers. Acoustic guitars use steel strings – because of this, the neck and body are typically made of heavier woods to withstand the tension from the tightness of the strings.
The steel strings used on acoustic guitars tend to bring a louder, crisper, brighter sound than the nylon strings of a classical guitar. As a result, they are generally used to create tons of folk, country and blues music – as well as certain genres of rock and roll.
Electric Guitar
Electric guitars are often similar in appearance to acoustic guitars – but they really don’t need to be. This is because electronic pickup is used to convert the sounds made by vibrating guitar strings into an electric current.
After this conversion, the signals are electronically altered to produce specific sounds before being fed to the amps. Because the sound of an electric guitar depends on electronic currents, the body of the guitar and the materials in which it is made can vary significantly.
An electric guitar uses steel strings, convenient for virtually any kind of music imaginable – from rock to country, and pop to jazz.
In general, acoustic and classical guitars are primarily used as accompaniment instruments, because (unlike electric guitars that are almost always accompanied with amplifiers) they are not loud enough to “compete with” other instruments.
However, some modern acoustic guitars have built-in electronics intended to amplify sound, which may then allow them to be focal rather than accompanying instruments.