A perfect cadence is a chord progression (or sequence of chords), placed at the end of a musical phrase or section, that travels from chord V (5, the dominant) to chord I (1, the tonic). For example, in the key of C major, a perfect cadence would go from G to C. There are many variations of a perfect cadence, such as different inversions of the chords or different chords that come before the V - I progression, such as IIb (chord 2, the supertonic, in the first inversion), or IV (chord four, the subdominant).

Sometimes, the V chord gains an added seventh (an additional note which is one minor third above the fifth note), giving it a slightly dissonant sound which has a natural 'pull' back to the tonic key (the original key). This is called a dominant seventh chord and is indicated by a superscript "7" beside the chord symbol.

The perfect cadence gained its name from its wholly 'finished' sound, which is why it is one of the most common cadences used at the end of a piece. It is not hard to find a perfect cadence, as they are so widely used- pick any popular modern song and it is likely that the V-I progression will be in there somewhere. Examples of a perfect cadence are:

- At the end of the happy birthday song (the dominant chord usually falls on the "to" and the tonic on "you")
- At the end of "We wish you a Merry Christmas" (dominant chord falls on "new" and tonic falls on "year")
- Vivaldi's Four Seasons (The end of the first movement of "Spring")
- The end of Handel's "Laschia Ch'io Pianga" aria

(With the first two songs it is recommended to look at the whole accompaniment instead of just the vocal line, even though the cadence is implied in the melody.)

You can sometimes identify a perfect cadence by the pattern in the bass line. It may move up to the tonic (the first note: for example, the note C if it is in C major) by the interval of a fourth, which sounds like the first two notes of, yes, "We wish you a Merry Christmas". It may also move up by step, depending on how the dominant chord is arranged (i.e which note is used in the bass line), or down by a the interval of a fifth. The important thing to note is that it always goes back to the original key- of the section, at least, if not the whole piece- and sounds like the music or phrase is finished, even if there is another phrase following it.