Quote from: MyOldGeForce on August 01, 2013, 12:10:36 PM

I recently started Bitcoin-Qt to receive my first payout from Slush's Pool on just over 0.1 BTC. To test how things work, I sent a small amount to one of my own addresses. I had to pay a 0.0005 fee too, and the only thing I could see in Bitcoin-Qt was "transfer to yourself" and the negative value of the fee. The balance was the same, minus the fee.

Then I went to Blockchain.info to see from what address it was sent, as I could not see that in Qt. I searched for the transaction number, and found my small transaction to another one of my addresses, but also a ~0.099 transaction to an address I do not recognize.

As I said, the balance in Qt is correct, but I don't own the unknown address, as far as I know.

This is probably a stupid question, I guess everything is as it should, but what happened?

The "unknown address" is also one of yours. Bitcoin-Qt pregenerates a set of 100 addresses (and only shows you the first one). Whenever you send a transaction, it takes an entire output (the term for some amount of incoming coin from a single transaction), sends whatever you specified to the recipient address and the rest to a change address, for which Bitcoin-Qt picks one of the pregenerated addresses.

This change address behavior can be quite confusing if you're new and it's not at all obvious what is going on without searching external sources for info (like this forum or the Bitcoin wiki).