What is the difference between black and white keys on a piano?

Black keys:

* Sharps (#): Raise the pitch of the white key to its right by a half step (semitone).

* Flats (b): Lower the pitch of the white key to its left by a half step (semitone).

White keys:

* Natural notes: Represent the letter names of the musical alphabet (A, B, C, D, E, F, G).