What is a Domain Name:
A domain name is an identification label that defines a realm of administrative autonomy, authority, or control in the Internet, based on the Domain Name System (DNS). Domain names are used in various networking contexts and application-specific naming and addressing purposes. Domain names are also used as simple identification labels to indicate ownership or control of a resource.
Country code top-level domain
A country code top-level domain (ccTLD) is an Internet top-level domain generally used or reserved for a country (a sovereign state or a dependent territory).
United Kingdom: .uk
All ccTLD identifiers are two letters long, and all two-letter top-level domains are ccTLDs. Creation and delegation of ccTLDs is performed by the Internet Assigned Numbers Authority (IANA) as described in RFC 1591, corresponding to ISO 3166-1 alpha-2 country codes with few exceptions .
Domain name registration:
The right to use a domain name is delegated by domain name registrars which are accredited by the Internet Corporation for Assigned Names and Numbers (ICANN), the organization charged with overseeing the name and number systems of the Internet. In addition to ICANN, each top-level domain (TLD) is maintained and serviced technically by an administrative organization, operating a registry. A registry is responsible for maintaining the database of names registered within the TLD it administers.
WHOIS (pronounced who is) is a query/response protocol that is widely used for querying databases in order to determine the registrant or assignee of Internet resources, such as a domain name, an IP address block, or an autonomous system number. WHOIS lookups were traditionally performed with a command line interface application, and network administrators predominantly still use this method, but many simplified web-based tools exist. WHOIS services are typically communicated using the Transmission Control Protocol (TCP).