The Internet Assigned Numbers Authority. A nonprofit that runs the root zone file — the master list of all TLDs and their nameservers. IANA is technically operated by ICANN, but acts as the canonical coordinator for domain name space, IP addresses, and protocol parameters.
Why it matters: IANA controls what TLDs exist and which registries operate them. No IANA approval, no TLD. That's it. IANA publishes the root zone file every day; your registrar's nameservers sync from it. If you're curious whether a registry is actually legitimate, check IANA's TLD list.
For bunkerdomains users: IANA's existence is why we can't invent TLDs. It's also why jurisdictional choice actually matters—registries answer to IANA, which means ICANN policy and US law cast a long shadow. Smaller, offshore registries sometimes push boundaries precisely because they sit further from ICANN's gaze.