Music
Music Theory
Chords

Chords

Chords

A chord is a group of notes played together. Most chords are built by choosing notes from a scale, such as the $\text{Do}$ major scale:

$$ \begin{matrix} \text{Do} & \text{Re} & \text{Mi} & \text{Fa} & \text{Sol} & \text{La} & \text{Si} \end{matrix} $$

The most common type is the major chord, which has a bright, stable sound. It’s formed by combining the 1st, 3rd, and 5th notes of the scale.

Major Chords in $\text{Do}$ Major

  • $\text{Do}$ Major: Formed from the $\text{Do}$ major scale. Take the 1st ($\text{Do}$), 3rd ($\text{Mi}$), and 5th ($\text{Sol}$) notes.
  • $\text{Fa}$ Major: Formed from the $\text{Fa}$ major scale. Take the 1st ($\text{Fa}$), 3rd ($\text{La}$), and 5th ($\text{Do}$) notes.
  • $\text{Sol}$ Major: Formed from the $\text{Sol}$ major scale. Take the 1st ($\text{Sol}$), 3rd ($\text{Si}$), and 5th ($\text{Re}$) notes.

$\text{Do}$, $\text{Fa}$, and $\text{Sol}$ are the primary chords in the key of $\text{Do}$ major. They’re used together in many songs because they share the same notes from the C major scale and sound naturally connected.

Every chord belongs to its own scale, but chords can also belong to a key together. When we say that $\text{Do}$, $\text{Fa}$, and $\text{Sol}$ are the primary chords in the key of $\text{Do}$ major, we mean that all their notes also appear naturally in the $\text{Do}$ major scale.

ChordNotesNotes in $\text{Do}$ major scale?
$\text{Do}$$\text{Do}$ – $\text{Mi}$ – $\text{Sol}$✅ yes
$\text{Fa}$$\text{Fa}$ – $\text{La}$ – $\text{Do}$✅ yes
$\text{Sol}$$\text{Sol}$ – $\text{Si}$ – $\text{Re}$✅ yes

Even though $\text{Fa}$ and $\text{Sol}$ can be built from their own scales, the notes they use still fit perfectly inside the $\text{Do}$ major scale. That’s why they “belong” to the key of $\text{Do}$ major — they don’t introduce any outside notes.

In the key of $\text{Do}$ major:

  • $\text{Do}$ is the I (one) chord — the root chord
  • $\text{Fa}$ is the IV (four) chord
  • $\text{Sol}$ is the V (five) chord

These three chords (I–IV–V) form the foundation of most songs.

Scales