The tritone can be used to avoid traditional tonality: "Any tendency for a tonality to emerge may be avoided by introducing a note three whole tones distant from the key note of that tonality." The tritone found in the dominant seventh chord can also drive the piece of music towards resolution with its tonic.

What is unique about the tritone?

The Definition of a Tritone

This interval is also unique because it is exactly half of an octave, which is 12 semitones. For example, the interval F – B is a tritone.

Why is a tritone the devil interval?

For centuries, it was called the devil's interval — or, in Latin, diabolus in musica. In music theory, it's called the "tritone" because it's made of three whole steps. ... But once music was no longer shackled to the church, it was free to express all kinds of tension. The devil's interval was ideal for that.