What is the difference between a public key and a private key?

In asymmetric cryptography, the public key and private key are a mathematically related pair. The public key is shared openly and used by others to encrypt messages intended for the key owner or to verify digital signatures the owner created. The private key is kept secret and used to decrypt messages encrypted with the matching public key or to create digital signatures. If someone encrypts a message with your public key, only your private key can decrypt it. If you sign a message with your private key, anyone with your public key can verify the signature.