Gotcha, thanks so much for the quick reply.

So, just made my first bitcoin transaction. Sent .01421 BTC from my Coinbase wallet to my Blockchain wallet. I then went to look at the blockchain to see the transaction, I see the sender address (1KT8QZSH9Q9CXaptRYMmTbXquy5CPTTBEJ) and I see the recipient address (16HVq7bNAQZ3iC1pD3reWXWySP9WbVubku), but there is a second recipient address shown in the same transaction. I have no idea what it is (1MQGhqUDafefcN3jFgNWnkZDqf5ydMm8ND) and it's for an amount that I didn't send (0.03819689 BTC). Can someone explain what this address is? I thought transactions would always be 1-to-1 (one sender address sends to one recipient address), but it looks like two transactions occurred simultaneously. Is this sender address not "mine" but rather an address owned by Coinbase?

Thanks!
Shaun