Guitar chords are dramatically simplified by the class of alternative tunings called regular tunings. In each regular tuning, the musical intervals are the same for each pair of consecutive strings. Regular tunings include major-thirds (M3), all-fourths, augmented-fourths, and all-fifths tunings. For each regular tuning, chord patterns may be diagonally shifted down the fretboard, a property that simplifies beginners' learning of chords and that simplifies advanced players' improvisation. The diagonal shifting of a C major chord in M3 tuning appears in a diagram.
The next step is to figure out what gauge, or thickness of string is best suited to your playing ability and style. Thinner gauges are easier to fret and bend, and may be better suited for beginners, until callouses build up on the fingertips. Heavier strings tend to produce greater volume and fuller tone. Nylon strings are typically categorized as light, medium or heavy tension. Steel strings for both electric and acoustic guitars are categorized by the gauge, or thickness of the lightest string, the high E string, measured in thousandths of an inch, with .09 being a common size for an electric set. A set of electric strings may be labeled .09-.042 - this is the gauge of the lightest and heaviest string in the set. Acoustic sets are a little thicker, so a typical medium-gauge set might be .012-.054.
Traditional electromagnetic pickups are either single-coil or double-coil. Single-coil pickups are susceptible to noise induced by stray electromagnetic fields, usually mains-frequency (60 or 50 hertz) hum. The introduction of the double-coil humbucker in the mid-1950s solved this problem through the use of two coils, one of which is wired in opposite polarity to cancel or "buck" stray fields.
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.