Mode ladder
The modes of a scale, all on the same root, from brightest to darkest. For the major scale each step down the ladder flattens exactly one note, so you can hear what that one note does. On the circle of fifths the seven notes are a window that slides one place at a time.
The root is at the top. Lit notes are the mode; gold rings are the notes that just moved, dashed rings where they came from.
C Dorian
From Mixolydian: E drops to E♭ (3 becomes ♭3).
C D E♭ F G A B♭ C
Often described as cool, hip and sophisticated: a minor sound with a bright sixth. Hear it in Miles Davis, "So What"; Santana, "Oye Como Va".
Same notes as B♭ Major.
The ladder
Past Locrian the next note to flatten is the root itself, and the ladder starts again a half step down: B Lydian has the same notes as C Locrian with its root lowered.