The WHOIS information of a domain is a collection of a number of details which are openly accessed via specific lookup Internet sites or a command line. The protocol which makes this possible carries the same name and you could easily see the company where a domain name 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 specific domain. All this information has to be legitimate and up-to-date constantly; if it's not the domain registration could be challenged. The latter is a policy of ICANN (the Internet Corporation for Assigned Names and Numbers), this means you should always ensure that the WHOIS details of your domain names are accurate. Updating the WHOIS for numerous country-code TLDs is limited, so when you register a brand new domain name, make sure you double-check the info you're submitting.