scale degree

The scale degree represents the relative relationships between notes in an octave. These are called the first, second, and so on, through seventh, and are represented by Roman numerals: I, II, III, IV, V, VI, and VII. A basic chord is made up of I, III, and V, regardless of the key used. For example, a chord in the key of C would use C, D, and F, while a chord in the key of F would use F, A, and C.