WHOIS is a protocol that makes it an easy task to view the details a specific domain has been registered with through a command line or using special web-based lookup websites. This info includes the names, address and e-mail address of the owner, administrator, tech and billing persons in addition to the registrar company the Internet domain has been purchased through, the creation and expiration dates. Aside from a few country-code TLDs that have certain limitations, the WHOIS details of any domain can be changed freely anytime, which is quite important given that according to the policies of the top-level Internet Corporation, ICANN, all details ought to be current and valid at all times. Inability to comply with these policies could lead to losing the ownership of a domain and in some cases a domain name might even be erased from the Domain Name System and released for free registration.
