The sound of an acoustic guitar is arguably the most well known in all of modern popular music. Without electronic components, the guitar relies solely on the interaction between the strings and the sound box to produce every note. Because of this, the strings of your acoustic guitar can significantly influence its sound. To get the most out of your guitar, keep an eye on the condition of the strings. You don't need to wait until your strings break to replace them. When they get old enough that their tone starts to change, it's time to re-string. Depending on the guitar, you may choose either nylon or metal strings. Nylon strings are the modern substitute for gut strings, so they're usually found on older styles of guitar such as baroque or flamenco. If you play the classical guitar, take care to fit it with the correct strings: since classical guitars are sized and tensioned differently from other varieties of acoustic guitar, they can be damaged by standard strings. Similarly, classical guitar strings won't work with other guitars. For metal-stringed guitars, there are several options available, each with its own acoustic character. The three most common types of metal strings are bronze, phosphor-bronze and silk-and-steel. The staple string for many guitarists, bronze produces a bright, quickly-fading tone that's lively and well-suited to any style of music. Phosphor-bronze is similar, but with added warmth and longer sustain. For a completely different sound, consider silk-and-steel. These strings create a tone that's gentle and mellow. Lower in tension and available in lighter gauges, silk-and-steel strings are easier to play and are great for vintage guitars that need special strings. It's also important to keep in mind the gauge of the strings you're choosing. Higher gauges are thicker, producing increased volume and extended sustain with an overall warmer tone. The trade-off of the rich overtones of heavy-gauge strings is that they are more challenging to play, requiring more force to fret, pick and strum. If you are an experienced guitarist, you likely have a preferred gauge already. If you're a beginner, it's a good idea to start with a lighter gauge to make the learning curve more forgiving. In the end, the right combination of material and gauge is a matter of personal preference. You may need to try several different acoustic guitar strings before you find the perfect ones for you, but the results will certainly be worth it.
The horizontal lines represent the frets on the guitar and the vertical lines represent the strings. The numbers listed let you know what fret number it is referring too. If there is an X it means don't play that string and if there is a 0 it means to play that string but do not press down on it anywhere. The black circles show you where to press down.

Electric guitars, introduced in the 1930s, use an amplifier and a loudspeaker that both makes the sound of the instrument loud enough for the performers and audience to hear, and, given that it produces an electric signal when played, that can electronically manipulate and shape the tone using an equalizer (e.g., bass and treble tone controls) and a huge variety of electronic effects units, the most commonly used ones being distortion (or "overdrive") and reverb. Early amplified guitars employed a hollow body, but a solid wood body was eventually found more suitable during the 1960s and 1970s, as it was less prone to unwanted acoustic feedback "howls". As with acoustic guitars, there are a number of types of electric guitars, including hollowbody guitars, archtop guitars (used in jazz guitar, blues and rockabilly) and solid-body guitars, which are widely used in rock music.
Flat-top or steel-string guitars are similar to the classical guitar, however, within the varied sizes of the steel-stringed guitar the body size is usually significantly larger than a classical guitar, and has a narrower, reinforced neck and stronger structural design. The robust X-bracing typical of the steel-string was developed in the 1840s by German-American luthiers, of whom Christian Friedrich "C. F." Martin is the best known. Originally used on gut-strung instruments, the strength of the system allowed the guitar to withstand the additional tension of steel strings when this fortunate combination arose in the early 20th century. The steel strings produce a brighter tone, and according to many players, a louder sound. The acoustic guitar is used in many kinds of music including folk, country, bluegrass, pop, jazz, and blues. Many variations are possible from the roughly classical-sized OO and Parlour to the large Dreadnought (the most commonly available type) and Jumbo. Ovation makes a modern variation, with a rounded back/side assembly molded from artificial materials.
The twelve-string guitar usually has steel strings, and it is widely used in folk music, blues, and rock and roll. Rather than having only six strings, the 12-string guitar has six courses made up of two strings each, like a mandolin or lute. The highest two courses are tuned in unison, while the others are tuned in octaves. The 12-string guitar is also made in electric forms. The chime-like sound of the 12-string electric guitar was the basis of jangle pop.
For example, in the guitar (like other stringed instruments but unlike the piano), open-string notes are not fretted and so require less hand-motion. Thus chords that contain open notes are more easily played and hence more frequently played in popular music, such as folk music. Many of the most popular tunings—standard tuning, open tunings, and new standard tuning—are rich in the open notes used by popular chords. Open tunings allow major triads to be played by barring one fret with only one finger, using the finger like a capo. On guitars without a zeroth fret (after the nut), the intonation of an open note may differ from then note when fretted on other strings; consequently, on some guitars, the sound of an open note may be inferior to that of a fretted note.[37]

Guitars have been played since the Renaissance era, after descending from the ancient Greek instrument, the kithara. Or, at least, that's how the theory goes: the only real proof for this is the similarities between the Greek word and the Spanish word, quitarra. Early guitars often had four strings, evolving into the six-string version we know today in the late 1600s. Anton Stradivari, the famous violin-maker, also had a hand in making guitars. There's now only one Stradivarius guitar left in existence.