1The padlock comparison
Think of the public key as an open padlock you hand out freely. Anyone can snap it shut on a message, but only your private key opens it.
2Signing works the other way
When you sign, your private key creates a mark that anyone with your public key can check but nobody else can forge.
3The one rule
Never share, upload or paste your private key anywhere. If someone asks for it, they are trying to take over your identity.
4Passphrase
Protect the private key with a long passphrase so a stolen file alone is not enough.
Lesson summary
Share the public key freely; the private key never leaves your device.
Looking for the current address? See the WeTheNorth link status.