What is natural major?

The whole tone semitone relationship between the eight tones of natural major: (full-full-half-full-full-full-half), so the natural major is 1 = (arbitrary) 1 2 3 4 5 6 7 1. Natural major is a collective term for a class of scales, not which ones can become.

d minor scale: 2 3 4 5 6 b7 1 2

e minor scale: 3 #4 5 6 7 1 2 3

g minor scale: 5 6 b7 1 2 b3 4 5

c minor scale: 1 2 b3 4 5 b6 b7 1

#f minor scale: #4 #5 6 7 #1 2 3 #4

#c minor scale : #1 #2 3 #4 #5 6 7 #1

f-minor scale: 4 5 b6 b7 1 b2 b3 4

#g-minor scale: #5 #6 7 #1 #2 3 #4 #5

bb-minor scale: b7 1 b2 b3 4 b5 b6 b7

Natural major (or C major if C is the dominant)

Natural major (or simply C Major)

Natural major consists of seven notes, Do, Re, Mi, Fa, Sol, La, and Si (or Ti) in the cantata, and C major is the "simplest" of the major keys, as it is the only major key that does not have any ascending (#) or descending (b) signs. C major is the most "simple" of the major keys because it is the only major key that does not have any ascenders (#) or descenders (b), and only requires playing the white keys on the piano. A minor key that is a minor third below a major key is called the relative minor of that major key (they have the same key signature).

Reference for the above: Baidu Encyclopedia-Natural Major