A chord, simply, is any combination of three or more notes. While two notes is technically harmony, they are not considered chords. Theoretically, any combination of notes is a chord, however, when used in a certain combination, some notes complement each other better than others. These notes are played together the most often, and make up the most popular chords. Because of the broad nature of this definition, types of chords have been developed that "sound good", in the western philosophy of music.
Types of chordsEdit
The following chords can be played in any key. To understand them, one should have the basic knowledge of a scale first. When considering what quality a chord is (major, minor, etc.), all that matters are the names of the 3 notes; it does not matter whether some notes are doubled or played in different octaves (known as a chord inversion). For example, a C major triad must have a C, an E and a G, but it doesn't matter which is on bottom, nor does it matter if there are 2 E's or 2 G's.
Other notes, such as 9ths and 13ths, can be added to a chord, but this learning resource focuses on basic chords and their structure.
The major triad is often symbolized with a capital letter (C). It is three notes: the first, third, and fifth note of a scale. Alternatively, you can figure this chord out by adding a note a major third (4 half-steps) up from the root note and then a minor third (3 half-steps) up from that. If you add the half-steps of a major and minor third you will notice the third note is 7 half-steps up from the root making a perfect fifth. This interval will remain the same in major and minor chords. All primary triads are created by stacking intervals of a third. It is a very whole sounding chord, and is found within most, if not all popular songs.
C Major triad: C - E - G
The minor triad is often symbolized with a lower case letter, or 'min', or just an 'm' (c | Cmin | Cm). It is composed of three notes: the first, flat-third, and fifth. The lowered third represents the third note of a minor scale. Alternatively, you can figure this chord out by adding a note a minor third (3 half-steps) up from the root note and then a major third (4 half-steps) up from that. The quality of this chord is not as full as the major chord, and has a darker complexion. It also is found in a majority of popular music.
C Minor triad: C - Eb - G
The diminished triad can be symbolized with either a '°' or with the abbreviation "dim" (C° | Cdim). Its components include: the first, flat-third, and flat-fifth. Alternatively, you can figure this chord out by adding a note a minor third (3 half-steps) up from the root note and then another minor third (3 half-steps) up from that. If you add the half-steps of two minor thirds together you will notice the third note is 6 half-steps up from the root making a diminished fifth, giving the chord its name. Having 2 lowered notes, a diminished chord does not have great euphony. It sounds slightly out of place, but adds a certain musical flavor.
C Diminished triad: C - Eb - Gb
The augmented triad is usually symbolized with a '+' or 'aug' (C+ | Caug). It is rarely seen in music, but considered one of the main chord structures. It combines: the first, third, and an raised fifth. Alternatively, you can figure this chord out by adding a note a major third (4 half-steps) up from the root note and then another major third (4 half-steps) up from that. If you add the half-steps of two major thirds together you will notice the third note is 8 half-steps up from the root making an augmented fifth, giving the chord its name. An augmented fifth sounds the same as a minor sixth but is notated differently and consequently will sound different in context. It has a very unique sound.
C Augmented triad: C - E - G#
Dominant Seventh ChordEdit
A seventh chord is attached to any other chord by the addition of the number '7' (C7). It can be attached to pretty much any chord, not just the major chord: (C7 | dim C7). Opposed to the addition of the seventh note of the scale, a flat-seventh note is added (in the key of C, this is Bb rather than B). When the third note is flat it is known as a minor 7. Therefore, "dominant 7" refers to a flattened seventh note, while a "minor 7" refers to both a flattened seventh and a flattened third note.
These chords, especially the dominant 7, tend to be popular in jazz and blues music, since they lend themselves to the "blues scale," which itself includes the flattened seventh note.
Dominant 7: C - E - G - Bb
Minor 7: C - Eb - G - Bb
Major Seventh ChordEdit
Like a dominant seventh chord, a note is added to the triad to create a major seventh chord. While a '7' represents the dominant seventh chord, the letters "maj" and a '7' represent a major seventh chord (C maj7). The note added to this chord is the seventh note of the root's major scale.
C - E - G - B
Minor Major Seventh ChordEdit
The minor major seventh chord (Cmmaj7) is used in Horace Silver's "Nica's Dream." It includes both a minor third note and a major seventh note.
C - Eb - G - B
The sixth chord is a four note chord, adding the sixth note of the root's major scale to a triad. Major and minor triads can become sixths, represented by the addition of a '6' (e.g. Cm6).
Major: C - E- G - A
Minor: C - Eb - G - A
Suspended (Sustained) ChordEdit
The suspended chord, also called sustained chord, is symbolized with "sus" or "sus4" (Csus | Csus4).
In the normal (major) triad in C, the note E is the "third" because is it an interval of a third above C. However, in suspended chords the "third" of the chord is replaced by a fourth. Traditionally the fourth would resolve to the third (E) of the chord, although the sus4 chord can stand on its own and doesn't always resolve to a normal triad.
A Csus chord is composed of the notes C, F, G instead of C, E, G (the normal triad).
Another version of this chord is symbolized with "sus2" (Csus2).
A sus2 with C as its root would be C, D, G.
Sus4: C - F - G
Sus2: C - D - G
This chord is just like a suspended chord in that it uses the second and fourth note. The difference is that, whereas in a suspended chord the third note is omitted, in an "Add2/Add4" chord, the third is kept.
Add4: C - E - F - G
Add2: C - D - E - G
Free tutorial on Chord Substitutions (dead link)