The WHOIS info of a domain is a collection of a variety of details that are openly accessed through special lookup websites or a command line. The protocol which makes this possible bears the same name and you may very easily see the organization where a domain has been registered, the creation, expiration and last update dates together with the names, postal and email address of those listed as Registrant (owner), Administrative, Technical and Billing contacts for a particular domain address. All of this info must be legitimate and up-to-date all the time; otherwise the domain name registration can be challenged. The latter is a policy of ICANN (the Internet Corporation for Assigned Names and Numbers), this means you must always make sure that the WHOIS details of your domains are valid. Updating the WHOIS for several country-code TLDs is limited, so any time you register a completely new Internet domain, make sure you double-check the info that you're submitting.