What is the primary purpose of the keys.info and keys.info.salt files?

I've been researching a little on backing up wallets. (My wallet was created via geth.) The official docs for geth say to "back up your keystore subdirectory." Fair enough, I can see my wallet and the data included for decrypting the private key included in it.

So the default directory (on Windows) is located at ~/AppData/Roaming/Ethereum. The files of interest in the structure are as follows:

Ethereum
   \
    |-keystore
    |      \-- Wallets   # Ok, I should save these files
    |\config.rlp
    |\history
    |\keys.info          # But what about these?
    |\keys.info.salt     # A salt would seem important
     \nodekey

What purpose do these keyfiles serve? Should I also back them up? Are they just a keyring of public wallet addresses, similar to how OpenPGP/GnuPGP save public keys?