Pretty Good Privacy (PGP) is a cryptographic software suite used for encrypting, decrypting, signing and verifying texts, e-mails, files, directories, and whole disk partitions. Its primary aim is to increase the security of e-mail communications. It was created by Phil Zimmermann in 1991.
PGP follows the OpenPGP standard (RFC 4880) for encrypting and decrypting data.
GNU Privacy Guard (GnuPG or GPG) is a free software replacement for the PGP cryptographic software suite. It is also compliant with RFC 4880.