Diminished chords have an “unresolved” feeling and seem to fell like they should be followed by something else, normally the following major chord.
A diminished chord consists of two minor thirds, so a minor third above the root note, and then a minor third above that. Most commonly, a diminished 7th would be played.
Locrian mode can be thought of as related in some way to the diminished chord.
-
A#
-
F
-
C
-
G
-
D
-
A
-
E
-
B
-
F#
-
C#
-
G#
-
D#


The Interactive Circle of Fifths by Hamish Haughey is licensed under a Creative Commons Attribution-Non-Commercial-No Derivative Works 2.0 UK: England & Wales License.