Domain Registrar
A Domain Registrar is a company which acts as an agent for the registration of Domain Names. Domain Names registered through authorized registrars are reported to the central registry, which can be queried via various tools such as whois. Once registered, only the domain's owner (or other authorized individuals) may make changes to the domain's registration properties, most importantly the DNS Servers used to determine the IP Address of the domain or its subdomains.
Ownership of registered domains is protected by a set of rules designed to ensure that the entity who has paid for the name retains control of the domain. Competition among registrars is fierce, and many of them resort to questionable tactics (e.g. Domain Registration Cuckoos) to acquire business.
Registrars
Acceptable
Registrars known to provide reasonable service at reasonable prices
Questionable
Registrars known to provide reasonable service at reasonable prices, but with issues