Authentic and plagal resolutions
An authentic cadence (V to I) is the strongest harmonic resolution in Western music. Playing a dominant chord followed by the tonic creates an irresistible pull toward closure. This is why almost every pop song, hymn, and classical movement ends with V-I. The ear demands it, and hearing V resolve to I feels inevitable and satisfying.
A plagal cadence (IV to I), often called the 'Amen cadence', is gentler and more contemplative. The subdominant moving to tonic creates a soft landing rather than a dramatic arrival. Church music favors this cadence because of its serene quality, and modern pop and rock use it to add warmth without drama.
Deceptive and half cadences
A deceptive cadence subverts expectation: V resolves not to I but to vi (the relative minor). This unexpected turn creates surprise and keeps a song moving forward when you expected closure. It is commonly used mid-song to prevent the music from ending too early.
A half cadence ends on V without resolving further, creating open-ended expectancy. It is often used at the end of an intro or the first line of a melody, setting up the expectation that more is coming. Understanding these four types gives composers and songwriters the harmonic grammar to shape emotional timing.