A registrant is the person or company who purchases a domain name. When registration is complete, the registrant gains the right to use that domain name for the time it is registered.  The registrant, along with the administrative, technical, and billing contacts for a domain, will receive all renewal and other administrative notices associated with the domain name. 

During the domain name registration process, you will be asked to provide the registrar with contact and technical information. The registrar will then submit the information to the central directory, also knon as the registry. The registry enters your information into their database so that other computers on the Internet can look-up the necessary information  to find your website.