The WHOIS info of an domain name is a collection of many details which are publicly accessed via specific lookup sites or a command line. The protocol which makes this possible has the same name and you could easily see the firm where a domain address has been registered, the creation, expiration and last update dates together with the names, postal and e-mail address of those listed as Registrant (owner), Administrative, Technical and Billing contacts for a particular domain name. All this info must be legitimate and up-to-date constantly; if it's not the domain name registration could be challenged. The latter is a policy of ICANN (the Internet Corporation for Assigned Names and Numbers), this means you should always make sure that the WHOIS details of your domain addresses are accurate. Updating the WHOIS for numerous country-code TLDs is limited, so whenever you register a completely new domain name, it is best to double-check the info you are submitting.