In order to reserve a domain, a registrant must register it with one of almost a thousand ICANN-accredited registrars. The registrar will check if the domain is available and create a WHOIS record with the registrant’s information. It is also possible to register domains through a registrar’s resellers.
The diagram below illustrates the main functions of the parties that are usually involved in the process.
A registrant is the person or organization who has registered the domain name. In order to do so, the registrant will usually apply online to a domain registrar or one of their resellers. The registrant is bound by the terms and conditions of the registrar with which it registers its domain name, for instance adhering to a certain code of conduct or indemnifying the registrar and registry against any legal or civil action taken as a result of use of the domain name. Registrants have certain responsibilities that are incorporated into these terms and conditions like payment of registration fees and submission and timely update of accurate data.
In addition to registering the name, registrants also need to have their domains listed on name servers in order to have that domain reachable on the Internet. A registrant is responsible for procuring or hosting his or her own name server if the registrar does not offer this service or he or she has opted out of the registrar’s service.
Registrars are organizations accredited by ICANN and certified by the registry operators to sell domains. They are bound by the Registrar Accreditation Agreement (RAA) with ICANN - and by their agreements with the registry operators. The RAA sets out responsibilities for the registrar including maintenance of WHOIS data, submission of data to domain registries, facilitating public WHOIS queries, ensuring registrants details are escrowed, and complying with RAA conditions relating to the conclusion of the registration period.
Some registrants may opt to register through a reseller. These are affiliated or under contract with registrars, and usually offer other services such as web hosting, email mailboxes etc. Resellers are bound by their agreements with the registrar(s) whose services they sell; they are not accredited by ICANN. However, the registrar for whom they are re-selling will still be the sponsor for the domain name registration and accountable for the domains sold by the reseller.
While registrars are contracted to conduct the day-to-day business of selling domain name registrations, registry operators are responsible for maintaining the registry for each TLD. The responsibilities of the registry operator include accepting registration requests (whether from registrars or directly from registrants), maintaining a database of the necessary registration data and providing name servers to publish the zone file data (i.e. information about the location of a domain) throughout the Internet.
The Internet Corporation for Assigned Names and Numbers (ICANN) is the international non-profit corporation that oversees the assignment of both IP addresses and domain names. It has responsibility for managing root server and TLD name system management and has contractual agreements with both registries and registrars that provide the foundation for the WHOIS system.