The domain name registrant is the organization or individual who registers the domain name. When you submit your request for a domain name, you become the registrant of the domain name.
The Registrar is the company that accepts your application for registration and reserves the domain for you at the main registry.
In the domain name registration process, you will be asked to provide the registrar with technical and contact information. The registrar will then send the information to the central directory, also known as a registry.
The registry enters your information into its database so that other computers on the Internet can search for the information needed to find your website.