IETF and ICANN, newest first
The IETF writes the technical standards the internet runs on — TLS, HTTP, DNS, email, routing. There is no membership and no fee. Anyone can join a mailing list and argue, and companies have influence only through the people they pay to show up.
A group chartered to solve one defined problem, then closed when it is done. It lives on a public mailing list, is run by volunteer chairs, and answers to an Area Director. The three meetings a year are useful, but the decisions happen on the list.
By rough consensus rather than voting. Chairs judge whether objections have been addressed, not whether more people said yes. That means a well-argued technical objection from one person can hold up work, and that a company cannot outvote anyone.
The same working groups, sorted by who has to care rather than by IETF area. Open a sector to see every group that touches it, and why it matters to that sector specifically. Groups appear in as many sectors as they are relevant to.
Participation is public but scattered. A company shows up in four different places, and each one means something different.
ICANN coordinates the domain name system: which top-level domains exist, who runs them, and the rules registries and registrars must follow. Unlike the IETF, its output is binding — policy takes effect through the contracts that registries and registrars sign.
A community of organised groups rather than individuals. Generic domains are handled by the GNSO, which is split into a Contracted Parties House (registries and registrars) and a Non-Contracted Parties House (business, intellectual property, non-commercial). Country codes sit with the ccNSO. Governments advise through the GAC, and security specialists through the SSAC.
Usually a Policy Development Process, or PDP: a chartered group working to a defined question, often with representative membership rather than open participation, meeting weekly or more. Slower and more formal than the IETF, and far fewer of them run at once.
Open policy development at ICANN, plus the standing bodies whose output tends to become policy later. Far fewer moving parts than the IETF, and each one lands directly on a contract.
Where adopted policy turns into contract language. Implementation Review Teams are open to volunteers, and this is usually the last point at which a requirement can still be shaped rather than absorbed.
ICANN participation is more legible than the IETF's, because people sit in named houses and constituencies and the rosters are published.