>>11510
PGP --> Pretty Good Privacy
https://en.wikipedia.org/wiki/Pretty_Good_Privacy
Fun fact on the side: I vaguely remember that use of PGP was made illegal in some countries back then (but might have changed by now).

public key vs. private key
https://en.wikipedia.org/wiki/Public-key_cryptography
In short, it essentially works like:
Someone wants to send sth encrypted to you, so they use your public key to encrypt it.
Upon receival, you can decrypt it with your private key.
It's an approach where a public key is only good enough for encrypting and the corresponding private key is necessary for decryption.