Chord Progression: A chord progression refers to any series of chords played in succession. It helps create musical structure and movement.
Tonic Chord: The tonic chord refers to the first scale degree or home base chord in a key. In an I-V progression, it is represented by the Roman numeral "I."
Dominant Chord: The dominant chord refers to the fifth scale degree chord in a key. In an I-V progression, it is represented by the Roman numeral "V."