What does verifying messages and signatures mean and how is it useful?
I see this all over thr community but need help grasping what exactly it is.
It's used to prove that you own a certain address, and therefore to prove your identity, this is why there is a thread in the meta section to "stake your address". So the idea is that you post a bitcoin public address that you control, someone quotes it for you, and then if a hacker hacks your account, they couldn't edit a quoted post of someone else, so what you would need to do is to sign a message with the quoted address.
I use Bitcoin Core to do this, it's really easy:
https://www.youtube.com/watch?v=3oxM9_OCQKMThere are two different things here:
1. Verifying messages with signatures, in connection with a bitcoin address: It's used for proving the ownership of a bitcoin address (and nothing in connection with identity like ID cards or similar). If someone asks you to prove that you own the bitcoins of an address, you can sign a message with your private key and you don't need to give out your private key, because the other party can check the validity of the signature with your public key. So if you want to buy something and you say you have 1 BTC in the address xxxxxxxxxxx, the seller can verify that the address is yours and you can really send the BTCs if the seller ships.
2. Verifying the ownership of the bitcointalk.org forum account: This is the procedure described in the quoted post, if you want to prove the ownership of the forum account, post your bitcoin address in that tread and you will have evidence that the forum account is linked to the given bitcoin address you have the private key of, and you can sign message to prove your ownership.
