> For the complete documentation index, see [llms.txt](https://guide.tonaly.app/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://guide.tonaly.app/songwriting/step-out-of-the-key/borrow-a-chord.md).

# In theory: Borrow a chord

{% embed url="<https://www.youtube.com/watch?v=rsQ9Ph6NXzY>" %}

▶️ **Intro**

Before composing a song, you will select a "Mode" for it. This could be "Ionian (natural major)", "Aeolian (natural minor)", Dorian, etc.

This "Mode" provides the tone-material for the song. A mode is always based on a scale. A basic scale that is used for composing does mostly have seven tones. You can build chords on this scale by layering thirds – or to put it more simply: By skipping every second tone of the scale.

So if you are composing within the key, you are only using seven different tones, and that's it. ☝️ **BUT** it can be nice and refreshing to use a chord that is **not within the key** and, thus, is using different tones and is based on a different scale.

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"Borrowed chords" is also called **"Modal interchange".**
{% endhint %}

### ▶️ **Borrow a chord – In theory**

You can **borrow a chord from a different scale** other than the scale your song is written in. The only thing you have to do is to use a different scale or key and create chords on this scale.&#x20;

👉 For example, you are composing a **song in "C Ionian major"** this scale will be the base of the chords and melodies:

<div align="left"><img src="/files/-M2hpl9cRqGpDJubGSm8" alt=""></div>

👉 You could go ahead and **borrow a chord from the "C Aeolian minor"** scale that has the following tones:

<div align="left"><img src="/files/-M2iOJpXTAsCDRCzCP3-" alt="This scale has three different tones other than the &#x22;C Ionian&#x22; scale."></div>

If we build chords on this scale by layering thirds, we will get different ones than with the Ionian scale (obviously).

For example, if we create a chord on the first tone of the "C Aeolian" scale, we will get a "C minor" chord. We can now go ahead and use this chord in our "C major" song.

<div align="left"><img src="/files/-M2iMzDG3nslN_y8B3yg" alt=""></div>

You can **build chords on any tone of the "C Aeolian"** or other scales and add them to your song. This is called "Borrow a chord" or Modal interchange.

### 👉 Further reading:

{% content-ref url="/pages/-M3zCJ2RHAmn4BEyBuYy" %}
[In the app: Borrow a chord](/songwriting/step-out-of-the-key/in-the-app-borrow-a-chord.md)
{% endcontent-ref %}