Perfect Cadence The perfect cadence is created by the sequence āV ā Iā (Dominant ā Tonic), therefore it is the strongest one. When it is preceded by a subdominant (II or IV degree), it is also called by authentic cadence.
plagal cadence [English] A chord progression where the subdominant chord is followed by the tonic chord . The "IV" represents the chord based on the fourth step of the scale and the "I" represents the chord based on the first step of the scale.