I'm trying to understand some basic concepts in the Bitcoin Core (v.0.15.1) and in the bitcoin "world".
I'm using a testnet, and used https://testnet.coinfaucet.eu/en/ to send some bitcoins to a "Receiving address". it worked fine, and I can see the transaction/balance changed in Bitcoin core.
However if I send bitcoins from coinfaucet to a "Sending address" (Which is a public key as I understand) then I can't see any bitcoins in that address and the balance is not changed and no transaction is reported, although coinfaucet shows me a verified transaction.
What am I missing? Can't the sending address hold/receive bitcoins? what are the "Sending address" used for if I can't send bitcoins to it?
I assumed that when I want to send funds from my wallet to someone, I first move funds from the Receiving address to the Sending address and use that address. but I'm totally unsure of this assumption.
Any help will be appreciated.
EDIT: After dinging some more, I came to realize that the Sending address is just addresses you have sent or planing to send to. It has nothing to do with the Change address as described in the answer. That is why after I sent money from coinfaucet to a made up sending address I did not see any change in balance because that address is not mine. and after a re-scan I see it a watch-only.