What are the 12 traditional pitch classes in music?

There are not actually 12 traditional pitch classes in music - there are only 7, which comprise those on the well known 'do, re, mi...' scale. Adding sharps or flats raises or lowers the pitch of a note, producing accidental pitch classes, but does not change the pitch class itself or create new pitches.

These pitch classes are:

C

D

E

F

G

A

B