a company or organization that processes domain name applications for a Top Level Domain (TLD) such as
a database that contains information about every registered domain name
A domain registry is a company that allows one to have their authoritative DNS servers be contacted by recursive name servers.
The 'Registry' is the system backend that is maintained by the operators of the TLD. Registrar's write new names to a central registry database, from which the authoritative root (essentially, a table of all domain names) is built. In the case of .com, .net and .org, the InterNIC runs the registry, and qualified registrars have shared access to it. In the case of many ccTLDs, the registry and registrar functions are combined within one entity.
an entity that receives domain name service (DNS) information from domain name registrars, inserts that information into a centralized database, and propagates the information in Internet zone files on the Internet so that domain names can be found by users around the world via applications such as the World Wide Web and email.