Chord symbols (for example, Cmaj7 or G6) are a type of notation used frequently in jazz and other areas of modern music to notate chord progressions and changes. This type of notation differs from that of classical music in that chord symbols don't show the function of a chord the way the Roman numeral notation does. Chord symbols, for modern music with lots of changes, are much easier to read. They function as a sort of shorthand for change-heavy music and are written with four chord parts in mind: the root, the quality, the extension, and the alterations.
The first part in chord symbols, the root, tells the musician which note is the root of the chord. In an E6 chord, for instance, the E serves as the root. Chord symbols also allow for inverted chords, or chords with a root other than the bass note. These chord symbols express that by showing the bass note with a diagonal slash under the original symbol.
Quality, the second part in chord symbols, denotes whether the chord is major, minor, diminished, or augmented. In a Cmaj7, the maj tells us that the C chord is major. The abbreviations for this area in chord symbols are maj, min, dim, and aug, respectively.
The extension in chord symbols, written after the quality, shows the musician if the chord differs from a triad (a third chord), such as an eleventh or seventh. This part of chord symbols is not always shown; if there is no indication of an extension, the musician is to assume that the chord is a triad.
The last part in chord symbols, the alteration, is usually but not always expressed. Think of this part as the "notes" section in chord symbols; it gives the musician any specific (and sometimes irregular) instructions for playing the chord and is always written in parentheses after the extension (or the quality, if no extension exists). For instance, (no fifth) would tell the musician that the chord is to be played with the fifth tone left out. Sus – short for “suspension”, would mean to play the 4th scale note instead of the 3rd. A minus sign would mean to lower (flat) a chord tone, such as C-9 which would mean to flat the 9th of the chord. Conversely, a plus sign would mean to raise (sharp) a particular chord tone.
Reading music using chord symbols allows a person to use written music as a map, rather than a note-for-note approach. By just reading the melody note and the chord symbols, musicians can improvise to their hearts content and create their own sounds on the keyboard.
The best of all worlds, however, is to be able to read music as it is written in a sheet music score, but also be able to read the chord symbols. Then the musician is free to choose which is best – the written part, or an improvised part. The sky is the limit for musicians who can do both.
