What is the definition of a subdominant chord?

The subdominant chord is defined specifically as a chord that has its root based on the subdominant degree of the scale in its key. In any given key, the subdominant is the fourth degree of the scale. For example, in the key of C major, the subdominant chord would be F major, since F is the fourth note in the C major scale. This chord plays a vital role in establishing harmony and creating movement towards the dominant chord, which in turn typically resolves to the tonic.

This understanding highlights the function of the subdominant chord within harmonic progressions. It does not necessarily need to resolve to the tonic but often does serve that purpose in various musical contexts. Additionally, the subdominant chord can be both major or minor, depending on the key, further expanding its role within compositions.