A guitar is a stringed instrument that produces sounds through the string's vibration resonating within the guitar's body.
Guitars can be classified into 3 kinds: the classical guitar, the acoustic guitar and finally the electric guitar.
The classical guitar (also referred to as the Spanish guitar) is the most common between the three kinds of guitar. This kind of guitar has a hollow body with a hole that acts as a resonator of the sound produced by plucking and strumming the strings. It normally has six strings made of nylon. These nylon strings have less tension when compared to steel strings thus making this kind of guitar easy to pluck or strum. It is assumed that it is to be played only with a person's fingers and not with a pick. It is also normally used without amplifiers but classical guitar owners can equip one or just play the guitar in front of a microphone. This kind of guitar is used mainly for classical, Latin and Flamenco music.
The acoustic guitar looks like a classical guitar in terms of shape and appearance. Like a classical guitar, an acoustic one does not normally use amplifiers. Their similarities stop there, though, as an acoustic guitar uses steel strings to produce a louder and brighter sound. Heavier woods (such as spruce, maple and mahogany) are used for the body and neck of the guitar. This is to withstand the tension brought on by the steel strings. This kind of guitar caters to blues, country and folk music. It can also be used in different genres of rock.
The electric guitar uses electronic pickups to convert the sound of vibrating the strings into electric current. These signals will then be electrically altered to produce the desired sound before being fed to the amplifiers. Since the electric guitar uses these pickups, there is no need for the body to be shaped in a way that it would act as a resonator. This type of guitar is used for different kinds of music such as rock and roll, country, pop, jazz and heavy metal.
Classical and acoustic guitars are normally used by one man or in accompaniment of other guitars. This is because, unlike electric guitars, classical and acoustic guitars are not loud instruments and they will not be able to compete with other instruments such as percussion and wind instruments. Acoustic guitars today, though, may have built-in electronics to allow amplification of the sound.