Invisible addresses with balance

[kwukduck]

Today i noticed that my total balance displayed doesn't match the balance of the sum of all the visible bitcoin adresses, also bitcoind didn't list those so i was wondering where this magic money came from.

I used Luke-jr's bitcoin test client and it showed some additional addresses with a balance and a groupbalance?

Why aren't these addresses shown by the default client or available in bitcoind somehow?
How does this happen anyway because i sure as hell didn't send anything to those addresses or received from somebody else at those for that matter.

Any insight would be helpful

[DannyHamilton]

When you send bitcoin, the client gathers up enough addresses from your wallet to EXCEED the amount you intend to send, it puts those coins into a transaction as an INPUT.  Then it puts the amount of coins you intend to send along with the receiving address you are sending to into the transaction as an OUTPUT.  It gets a new address from your wallet, and sends the extra coins there.  The "receiving addresses" that you see in the client are addresses that you chose to generate so that you could give the address to someone else and they could send coins to you.  These addresses where the change from a transaction are sent aren't addresses you have chosen to generate to give to someone else, so they don't show in the client, but they are still in your wallet file.

Or at least that is my understanding of it.  If I'm wrong someone will be by shortly to correct me.