The central database is typically referred to as the ‘registry’, and it provides registration service and management functionality to registrars through a secure interface. These registrars, such GoDaddy, 1&1, or Network Solutions, in turn provide a web interface to the registrant. The registrant is the individual or business that ‘owns’ the domain name and can administer it through their interface.

The supply chain looks a little like this from a very high level:

There is often an optional layer between the registrant and the registrar, called a reseller.