The IETF is open to any interested individual. The IETF Mission Statement is documented in RFC 3935.
The technical work of the IETF is done in its working groups, which are organized by topic into several areas (e.g., routing, transport, security, etc.). The IETF areas are managed by Area Directors, or ADs. The ADs are members of the Internet Engineering Steering Group (IESG).
Much of the work in the IETF is handled via mailing lists. The IETF holds meetings three times per year. IETF Hackathons encourage collaboration on developing utilities, ideas, sample code, and solutions that show practical implementations of IETF standards.
The Internet Society provides a corporate home for the IETF Administration LLC (IETF LLC), the entity that supports IETF, the Internet Architecture Board (IAB), and the Internet Research Task Force (IRTF), and supports the work of these groups through a variety of programs.