The very basic definition of a "chord" is a combination of three or more pitches sounded simultaneously. Chords are built from musical scales, and are one of the foundations of guitar playing. Knowing the basic music theory bolstering chords and their construction will help guitarists get the most out of exercises and techniques for chord playing that will make them better musicians.

Major chords consist of the first (root) note of a major scale along with the third and fifth notes. For example, because the C major scale contains the notes "C, D, E, F, G, A and B," the major chord for this scale would consist of the notes "C, E and G" played simultaneously. Major chords are written without a chord-type symbol and with a capital letter; thus a note of "C" marked on a guitar chord sheet would imply the C Major chord. A minor chord consists of notes within the minor scale, more specifically again the root, third and fifth notes. Since the notes of the C minor scale are "C, D, Eb, F, G, A, B" the minor chord for the key of C would contain the notes "C, Eb, G." A minor chord will be marked with the name of the chord followed by a lower-case "m."

Three-note chords such as the ones mentioned are called "triads," but there are many other types of chords. The common denominator of chords it that they are all relative to musical scales. Whether the chord is a Major 7th, Augmented, 9th, Minor, Diminished, or other type of chord, it has its own unique symbol. The following lists basic chord types, their constructions (based on notes of the musical scale) and symbols:

Type	Symbol	Construction
Major	*	1-3-5
Minor	m	1-b3-5
Seventh	7	1-3-5-b7
Major Seventh	M7	1-3-5-7
Minor Seventh	m7	1-b3-5-b7
Ninth	9	1-3-5-b7-9
Major Ninth	M9	1-3-5-7-9
Minor Ninth	m9	1-b3-5-b7-9
Sixth	6	1-3-5-6
Minor Sixth	m6	1-b3-5-6
Diminished	(dim) or simply "-"	1-b3-b5-b7
Augmented	(aug) or simply "+"	1-3-#5

All chords can have a variety of different "voicings," which simply denote the different variations of chords depending on where they are played on the fret board and in what combination of notes. To ease reading, playing and practicing for guitar players, guitar chords are written as Chord Blocks and symbols instead of in standard musical notation.

The Chord block is a recreation of the neck of the guitar, and the vertical lines on the block are representative of the six strings - E-A-D-G-B-E - of the guitar. Chord blocks are the basic ways guitar chords are noted, and with practice, guitarists can memorize the different chords so they recognize them on-sight by the way they look as a chord block instead of having to read individual notes. Chord structures that require multiple notes across all six strings are called barre chords, and are played by using the index finger to create a bar across all six strings and ease the process of playing.

Exercises for Playing Chords and Tips for Improving Technique

Becoming good as a guitarist at playing chords starts with learning the basic music theory that underpins them, and diligently practicing. While every musician knows practice is truly the key to success as a guitar player, most do not understand that only by understanding the complex concepts behind music can a guitarist truly excel and learn to simplify techniques for playing and transitioning between chords quickly and efficiently. Practice is of no use to the guitarist that does not use the fundamental laws of music, even to inspire innovation.

The following are three good tips and exercises for practicing chords and improving overall technique:

Guitarists should practice not only chords, but also their foundations - scales and arpeggios. Having a chord dictionary can help to establish the many different combinations of chords that exist, but it cannot in and of itself fully explore the basic elements upon which chords are based. Some guitarists might want to systematically run through the different arpeggios and scales by key signature or simply by natural progression upwards on the guitar. Others might create a combination of chords from a favorite song and play all scales and arpeggios attached to the key signature of the song or the chords within it.
Musicians need to focus on their weaknesses when practicing. Some guitarists might be naturally inclined towards learning songs by ear and memorizing hand positions for chords rather than individual notes. For these types of guitarists, learning scales and arpeggios might be more challenging than for others that might naturally think about individual notes instead of hand positions when it comes to chords. Those that are "linearly challenged" in this way might spend more time practicing scales than chords and arpeggios to make the scales more familiar and less intimidating.
Rhythm and timing is important for improving chords, and guitarists should work with a metronome whenever possible to help with scales and arpeggios and to quicken the transition time between chords. Speed is not important at the beginning - the critical component of this type of practicing is staying on rhythm and learning to focus on the "feel" of playing, not just notes and hand positions.
Those guitarists that learn the basics of music theory and implement them into directed practice techniques will improve exponentially. Inspired playing and creative improvement will emerge naturally from those musicians seasoned in all elements of guitar chords.