Someone's asking for my extended public key.
How do I view this?
What are the consequences of giving this to someone? Can they steal my Bitcoins if I give this to someone?
How do I view my extended public key?
Go to Wallet > Master Public Keys, and copy the text that starts with
What are the consequences of giving my extended public key to someone?
They can view all of the transactions and addresses in your wallet. They can generate as many of your addresses as they want.
Can they steal my Bitcoins if I give this to someone?
No, unless you also give them one of your private keys. (All of your private keys are equivalent if they have access to your extended public key.) So, don't do that.
I want to reiterate what @NickODell said: DO NOT share your private key.
This rule - to clarify - is not referring to the master private key (
xprv): it means any child address' private key (WIF, hex, etc) will compromise your whole chain, as outlined here.
One could understandably assume that because an address has been used and "discarded", that less caution with that old private key is fine (because you'll never use it again). Don't fall into this trap!