(1) The specific pitch of each note in the notation is called the key; In the staff, the specific position of the relationship between the basic tones on the staff is called the key. These two definitions look different on the surface, but in fact they are exactly the same, because there is a one-to-one correspondence between the notes in the notation and the notes in the basic level. At this time, the tone only defines seven tones, which does not include the factor of mode. For example, c key, d key and so on.

(2) The specific pitch position of each tone in the mode is called the key. The name of the key consists of two parts, namely, the mark of the tonic and the mark of the mode. For example, C major, A minor; D major, b minor and so on.