Question. What is PGP?
Answer. PGP stands for Pretty Good Privacy. It is used to encrypt and decrypt data.
Question. What is GPG (or GnuPG)?
Answer. GPG stands for Gnu Privacy Guard (also called GnuPG). This is an open source substitute for PGP.
Phil Zimmerman, creator of Pretty Good Privacy (PGP) interview:
PGP software may be obtained via:
• www.gnupg.org This is open source software that is a full replacement for PGP. It is free but does not use a graphical interface – it is command line only. (used primarily on UNIX type systems)
This is generally how PGP using it with email, it can be used to transfer other types of files: