ICANN (the Internet Corporation for Assigned Names and Numbers) is the nonprofit organization that oversees the global domain name system's core policies; it's the reason domain registration works the same basic way no matter which registrar you use.

ICANN doesn't sell domains itself and isn't who you interact with day to day. Instead, it accredits registries (the organizations that operate specific TLDs, like Verisign for .com ) and registrars (the companies, like NameBright, that sell domain registrations to the public), and it sets the baseline rules both have to follow: the transfer process between registrars, the post-expiration grace and redemption periods, WHOIS/RDAP data requirements, and dispute-resolution policy (UDRP).

The practical effect for a domain owner: a lot of what can feel like a registrar's arbitrary rule, like the 60-day transfer lock or the redemption fee structure, is actually an ICANN-mandated policy that every accredited registrar has to implement.