Public Key

A public key is a value you can share openly that lets others send you scrambled messages or check your digital signature, and it always comes paired with a private key you keep secret. Anyone can use your public key to lock a message that only your private key can unlock.

It is like a postbox slot on the street: everyone can drop letters in, but only you hold the key to open the box and read them. Public keys matter because they let strangers communicate and verify each other securely over the internet, without ever having to share a secret in advance.