In public-key cryptography, what are the two keys called that a user has?

In public-key cryptography, a user has a public key and a private key, two mathematically linked keys. Data encrypted with someone's public key, which can be shared openly with anyone, can only be decrypted using their matching private key, which they keep secret, allowing two people who have never met to establish a secure connection.

Master keys, session keys, hash keys, and cipher keys are terms used in other areas of cryptography and computer security, but they don't describe the specific public-and-private key pairing that defines public-key cryptography itself.

This system underpins the padlock icon you see in a web browser during secure HTTPS browsing, as well as digital signatures and cryptocurrency wallets, making it one of the most widely used pieces of math in everyday technology.