A sponsored top-level domain operated by a designated organization on behalf of a specific community or industry. ICANN created this category to let groups manage their own TLDs rather than relying on generic registries.
Common examples: .edu (educational institutions), .gov (U.S. government), .museum (museums), .aero (aviation), .coop (cooperatives). Each has its own registry and eligibility rules—you can't just register anything under .edu.
Why it matters: sTLDs are heavily regulated and community-gated. They're not bulletproof; they're the opposite. If you're running a privacy service, journalism outlet, or free-speech project, sTLDs will reject your application or revoke your domain under pressure. Sponsored registries answer to their communities and ICANN compliance first.
For bunkerdomains use: skip sTLDs entirely. Go gTLD, ccTLD, or new gTLD instead. You need jurisdictional independence and registry operators who won't fold when lawyers call. sTLDs are designed for institutional legitimacy, not anonymity.