A domain name registrar is an organization or commercial entity, accredited by both ICANN and generic top-level domain registry (gTLD) to sell gTLDs and/or by a country code top-level domain (ccTLD) registry to sell ccTLDs; to manage the reservation of Internet domain names in accordance with the guidelines of the designated domain name registries and to offer such services to the public.
Domain registration information is maintained by the domain name registries, which contract with domain registrars to provide registration services to the public. An end user selects a registrar to provide the registration service, and that registrar becomes the designated registrar for the domain chosen by the user.
Only the designated registrar may modify or delete information about domain names in a central registry database. It is not unusual for an end user to switch registrars, invoking a domain transfer process between the registrars involved, that is governed by specific domain name transfer policies.
Registration of a domain name establishes a set of Start of Authority (SOA) records in the DNS servers of the parent domain, indicating the IP address (or domain name) of DNS servers that are authoritative for the domain. This provides merely a reference for how to find the domain data – not the actual domain data.
Registration of a domain does not automatically imply the provision of DNS services for the registered domain. Most registrars do offer DNS hosting as an optional free service for domains registered through them. If DNS services are not offered, or the end-user opts out, the end-user is responsible for procuring or self-hosting DNS services. Without DNS services for the domain, the registration is essentially useless for Internet services, although this situation is often encountered with domain parking and cybersquatting.