OpenPGP is a non-proprietary protocol for encrypting email using public key cryptography. It is based on PGP as originally developed by Phil Zimmermann. The OpenPGP protocol defines standard formats for encrypted messages, signatures, and certificates for exchanging public keys.
Beginning in 1997, the OpenPGP Working Group was formed in the Internet Engineering Task Force (IETF) to define this standard that had formerly been a proprietary product since 1991. Over the past decade, PGP, and later OpenPGP, has become the standard for nearly all of the world's encrypted email.
By becoming an IETF Proposed Standard (RFC 4880), OpenPGP may be implemented by any company without paying any licensing fees to anyone.
The OpenPGP Alliance brings companies together to pursue a common goal of promoting the same standard for email encryption and to apply the PKI that has emerged from the OpenPGP community to other non-email applications. OpenPGP Alliance members do not have to feel that they are going it alone. They can be encouraged by the power of their numbers, to be visible to each other and work together toward a common goal, making each other stronger in the face of competing email encryption standards and competing approaches to building a Public Key Infrastructure. All this helps demonstrate to decision makers in the industry that OpenPGP really is the leading standard.