Borrowed chords
Steal a chord from the parallel key.
Steal from the parallel key
A borrowed chord comes from the parallel minor or major. It's the quickest way to make a vanilla progression sound surprising.
Common steals
iv minor four, the "Beatles" chord ♭VI the big cinematic lift ♭VII the rock anthem chord ♭III the dramatic dark turn
Why it matters
Borrowing is why "same four chords" can still feel brand new. One chord from next door and the whole room changes color.