"The Official PGP User's Guide" is the user's manual for PGP (Pretty Good Privacy) public-key cryptography software, freely available over the Internet, that has become the de facto standard for the encryption of electronic mail and data. PGP and its author, Philip Zimmermann, are the focus of national and international debates concerning this new, powerful "envelope" that allows individuals the same privacy in communications as enjoyed by governments and large corporations. Because cryptographic software is considered munitions by the U.S. government, and is thus subject to the same export restrictions as tanks and submarines, the worldwide distribution of PGP over the Internet has raised a host of issues that are addressed in the "User's Guide.". In addition to technical details, the "User's Guide" contains valuable insights into the social engineering behind the software engineering and into the legal, ethical, and political issues that have surrounded PGP since its initial release.