Borrowed chords are another method composers use to add an element of color and surprise to harmony. This procedure, also known as “modal mixture,” is when a composer borrows a chord from the parallel key (a major or minor scale with the same tonic).
You are likely familiar with the most common type of borrowed chord, the Picardy third (also known by its French title, the tierce de Picardie). This is when major chord I appears in a minor key, often at a final cadence.
In major keys, the most common borrowed chords from the parallel minor mode are:
Commit these facts to memory for easy recall.