This article is from the Piano General Topics FAQ, by Isako Hoshino firstname.lastname@example.org with numerous contributions by others.
There is a simple alpha-numeric notation system which has
been in existence for some time and which may be used in
postings on the Internet. It is as follows:
Going up starting at middle C: c1 d1 e1 f1 g1 a1 b1 Continuing up the next octave: c2 d2 e2 f2 g2 a2 b2 And the octaves above that: c3 etc. ...and so on... First octave below middle C: c d e f g a b Next octave lower: C D E F G A B Next octave lower: C1 D1 E1 F1 G1 A1 B1