A diminished chord is a type of chord that consists of three notes: the root, a minor third, and a diminished fifth. This unique structure creates a tense and unstable sound, often used to build suspense in music. Diminished chords are commonly represented with the symbol "°" or "dim." In music theory, diminished chords can be found in various genres, including classical, jazz, and rock. They often serve as transitional chords, leading to more stable chords. The use of diminished chords can enhance emotional expression and add complexity to a musical piece, making them a valuable tool for composers and musicians alike.