A chord is a combination of three or more tones sounded together in harmony. Some of these guitar chords are the keys of C, D, E, F, G, A, and B majors, minors, dominant 7th, major 7th, minor 6th, diminished 7th, augmented 7th, dominant 9th, major 9th, minor 9th, suspended 4th, and 7th suspended 4th. The basic chords are grouped into chord families (keys): A, D, E (A Family); D, Em, G, A (D Family); G, Am, C, D, Em (G Family); and C, Dm, Em, F, G (C Family).
All of these chords can be shown in a chord chart. A guitar chord chart is a graphical representation of a rectangular box that shows you how to play each single chord. A comprehensive understanding of guitar chord charts is vital to any guitar player.
The elements of a chord chart are these: the six lines that run vertically represent the strings; the series of lines running across the string lines represent the frets; the crisscross of the string and fret lines represent the guitar fret board; the dots located on the fret board show which strings and frets to press; a double line at the right edge of the box represents the end of the neck; an x symbol on the string line means dead string, or do not pluck this string ; an o symbol on the string line means open string, or the string is plucked but not fingered; numbers 1 to 4 on the string line corresponding to the dots specify which finger to press on that string. Number 1= the index, 2 = middle, 3=ring, and 4= the pinky; a line crossing two or more strings is called a barre chord , in which one finger presses several strings.
From this basic information, you can learn to form and play any guitar chord, and thus master guitar playing.