[Registry]
Registry is an organization that manages the administrative data for the TLD domains. Each domain has an associated registry, such as “.com / .net” are managed by VeriSign. Registrars are requested to ensure that SRS(※1)  could be accessed equally, and to stay neutral position.

[Registrar]
ICANN’s(※ 2) designated Registrar is domain registration service provider, and directly contracted with a Registry. Running their business based on ICANN’s Registrar Accreditation Policy and Registrar Accreditation Agreements, and have sufficient resources, motivation, technical skills and business ability. Registrar can make contract with a Registry (Registry-Registrar Agreement), and register domain information directly to the Registry database through SRS.

※ 1 SRS (Shared Registry System) is software for an unlimited number of registrars to compete in the domain name registration business by using one shared registry. The system is based on the agreement between Registry and U.S. Government. Registrar which is designated by ICANN, and contracted with Registry (Registry-Registrar Agreement), is allowed  to operate their business.

※ 2 ICANN refers to the Internet Corporation for Assigned Names and Numbers. It is a nonprofit established by the US government to keep the internet functioning, a big component of which involves maintaining unique identifiers.