When the key pair is used for encryption, the sender uses the public key to encrypt the message, and the recipient uses the private key to decrypt the message. When the key pair is used for signing, the signer uses the private key to encrypt a representation of the message, and the recipient uses the public key to decrypt the representation of the message for signature verification.
Private Key and public key are part of encryption that encodes the information. Both keys work in two encryption systems called symmetric and asymmetric. Symmetric encryption (private-key encryption or secret-key encryption) utilize the same key for encryption and decryption. Asymmetric encryption utilizes a pair of keys like public and private keys for better security where a message sender encrypts the message with the public key and the receiver decrypts it with his/her private key.
Example of usage – “Public and Private key pair helps to encrypt information that ensures data is protected during transmission.”