In music theory, a cadence is a series of chords that brings a sense of resolution or conclusion to a musical phrase or section. An interrupted cadence, also known as a deceptive cadence, is a type of cadence that creates a temporary sense of suspense or surprise by deviating from the expected resolution. It is called "interrupted" because it interrupts the expected progression, and "deceptive" because it deceives the listener's expectations.

An interrupted cadence typically occurs at the end of a phrase or musical section, where the listener anticipates a strong resolution to the tonic (the main or home key of the piece). Instead of resolving to the expected tonic chord, the interrupted cadence moves to a different chord, often a chord that is closely related to the tonic. This unexpected chord creates a momentary tension or surprise before the music eventually resolves to the tonic.

The most common example of an interrupted cadence is the progression from a dominant chord (V) to a chord other than the tonic (I). In a typical major key, the dominant chord is built on the fifth scale degree, and the tonic chord is built on the first scale degree. So, the expected resolution would be from V to I, creating a strong sense of finality. However, in an interrupted cadence, the progression might go from V to vi (the relative minor chord) or to any other chord that is not the tonic.

For example, in the key of C major, the dominant chord is G major (V) and the tonic chord is C major (I). An interrupted cadence might involve the progression G to Am (vi), instead of the expected G to C. This unexpected change creates a moment of tension or surprise before resolving to the tonic.

Here is a simple example of an interrupted cadence in the key of C major:

| C | G | Am | F | C |

In this example, the progression from G to Am (instead of G to C) creates an interrupted cadence. The listener expects the music to resolve to C, but it temporarily moves to Am before finally resolving to C.

Interrupted cadences can also occur in minor keys, where the expected resolution would be from a dominant chord to the tonic chord. For example, in the key of A minor, the dominant chord is E major (V) and the tonic chord is A minor (i). An interrupted cadence might involve the progression E to F (bVI), creating a surprising deviation from the expected resolution.

Overall, interrupted cadences provide a moment of tension, surprise, or unexpected twist in a musical phrase, adding variety and interest to the music.