Tritone: The tritone is an interval of three whole steps, also known as an augmented fourth or diminished fifth. It has a very dissonant and unresolved sound.
Altered Chords: Altered chords are chords that have one or more notes modified by raising or lowering them by a half step. They create unique and unexpected sounds.
Enharmonic Equivalents: Enharmonic equivalents are different ways to notate the same pitch. For example, C# (C sharp) and Db (D flat) are enharmonic equivalents because they represent the same piano key but with different names.