second-level domain

The human-readable label you actually register, sitting directly left of the TLD. In example.com, 'example' is the SLD; in mail.example.com, 'mail' is a subdomain. You own the SLD for a registration period (usually 1–10 years); the registry maintains the TLD infrastructure. SLDs are what you pay for, what you point at nameservers, and what you lose if you don't renew. They're the practical unit of domain ownership. Most people confuse 'domain' with 'SLD'—technically imprecise, but the distinction matters when you're reading registry docs or troubleshooting DNS. Under ICANN's model, you never own the TLD itself; you lease the SLD from a registrar, which coordinates with the registry. Some TLDs (like most ccTLDs) have residency or local presence requirements tied to the SLD. Others (most gTLDs) don't care. If you're registering anonymously through bunkerdomains, you're buying the right to use an SLD without KYC friction—the registry still tracks it, but we don't hand them your passport.