The WHOIS info of an domain name is a collection of a variety of details that are publicly accessed using specific lookup websites or a command line. The protocol that makes this possible bears the same name and you may very easily see the company through which 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 specific domain address. This info ought to be legitimate and up-to-date all the time; if it's not the domain address registration may be challenged. The latter is a policy of ICANN (the Internet Corporation for Assigned Names and Numbers), so you should always make sure that the WHOIS details of your domains are legitimate. Updating the WHOIS for a number of country-code TLDs is limited, so whenever you register a completely new domain name, you ought to double-check the info that you are submitting.