The Registry is an organization responsible for the overall administration of top-level domain names. They create domain name extensions, set the policies and rules for the domain names, and work with registrars to sell them to the public.
A registry can manage multiple domains, such as VeriSign for .com and .net, or just one domain, such as SIDN for .nl.
Examples of a few registries that manage popular top-level domains,
- VeriSign
- DotSpace
- Donuts
The Registrar, also known as the middleman, is an accredited (by ICANN) organization, like Z.com, that sells domain names to the public (you!). Some can sell TLDs such as .com, .net, and .org, or ccTLDs such as .us, .sg and .ph.