Fig. 1         C             D             E             F             G             A            B                     1             2              3             4              5              6             7

Figure 1 shows the c major scale. Each scale degree can be referred to by number.

Fig. 2

Figure 2 shows naturally occuring thirds built on each scale degree. Use of the word naturally here refers to the fact that the notes all come from the scale they are built upon.

Fig. 3         C             D             E             F             G            A            B                     I              ii             iii            IV            V            vi            vii

Figure 3 shows naturally occuring triads built on each scale degree . Simply another stacking of a naturally occuring third on top of the first stacking of a naturally occuring third (shown inFigure 2 ). Each triad can be referred to by a number (e.g. one chord, two chord, three chord, etc.), in this case roman numerals are commonly used. Note that triads are chords (three note chords [four note chords are not triads]).