In music theory, "chord functions" refer to the roles that chords play within a key or progression. Each chord can create tension, resolution, or movement, influencing how a piece of music feels. The three primary functions are tonic, dominant, and subdominant. The tonic chord provides a sense of rest, the dominant chord creates tension that seeks resolution, and the subdominant chord serves as a bridge between the two. Understanding chord functions helps musicians and composers create effective progressions. For example, in the key of C major, the C major chord functions as the tonic, the G major chord as the dominant, and the F major chord as the subdominant. This framework guides the emotional flow of music.