Have you ever heard a song and felt like something unexpected happened in the music? That's probably a tritone substitution!
A tritone is a special interval in music that sounds really dissonant and creates a lot of tension. It's made up of two notes that are six whole steps apart from each other, like the notes C and F#.
Now, imagine you're playing a song and you get to a part where the music is heading towards a certain chord, like a G7. But instead of playing the G7, you play a different chord that sounds similar but creates a different feeling. That's a tritone substitution!
To do this, you'll need to find a chord that's a tritone away from the chord you were originally going to play. So if you were going to play a G7, the tritone substitution chord would be a Db7. Even though these chords have different notes, they share the same tritone interval, which gives them a similar sound.
A tritone substitution can add a lot of interest and surprise to music. It's like a musical twist that keeps you on your toes!