What is a Chord?

A chord is a combination of three or more notes. They are built off a single note, called the root. A chord composed of three notes is called a triad, and it consists of the root, the third, and the fifth notes of its scale. Chords with four or more notes are called extended chords. The common chords, C, G, D, A, and E, are all major triads. (not major in the significant sense, major in the music theory sense)

A major triad is composed of the root, a major third and a perfect fifth.

To find the major third, count up four half steps from the root. The root can be any of the notes on the musical scale. To find the perfect fifth, count up seven half steps from the root. For example, if your root note is a B, then your major third will be Eb. Your perfect fifth will be Gb. When you add these three together, you get your major triad.

There is also such a thing as a minor triad. It is created with the root, a minor third and a perfect fifth. To find the minor third, count up three half steps from the root. To find the perfect fifth, count up seven half steps from the root, just like you did for the major triad. If your root is the note E, your minor triad will have G for its minor third and B for its perfect fifth. 

The augmented triad and the diminished triad are also used. They are not super common, because you can work your way around them, but they are useful to know nevertheless since you may run into them sometime. The augmented triad is created with a major third and an augmented fifth. The difference between an augmented fifth and a perfect fifth is that the former is raised one half step. To find the augmented fifth, simply find the perfect fifth of your root and add a half step.

To find a major third, count up four half steps from the root, as shown in the section on major triads. 

The diminished triad is created with a minor third and a diminished fifth. A diminished fifth has one less half step than a perfect fifth. To find the diminished fifth, find the perfect fifth and subtract a half step.

To find a minor third, count up three half-steps from the root as shown in the section on minor triads. 

So here is your group of triads with the three notes that make them up:

MAJOR-Root, Major 3^rd, Perfect 5^th

MINOR-Root, Minor 3^rd, Perfect 5^th

AUGMENTED-Root, Major 3^rd, Augmented 5^th

DIMINISHED-Root, Minor 3^rd, Diminished 5th

In our next post, I will discuss how you can use this information to find what chords make up a key and how to find what key you're playing in. This is not useless information, it has several practical applications. 

Quiz: What is the Perfect 5th of a minor triad where Gb is the root note?