Pretty Good Privacy (PGP) and GNU Privacy Guard (GPG) are two cryptographic software tools that enable data encryption, authentication, and integrity. These tools primarily secure email communications and transfer files. In the case of the latter, PGP and GPG can be particularly useful in providing data-in-motion security for unencrypted file transfer protocols like FTP and HTTP. They also provide data-at-rest encryption for files stored in a file transfer server.