The WHOIS information of a domain name is a collection of various details that are freely accessed through special lookup sites or a command line. The protocol which makes this possible has the same name and you may easily see the company where a domain has been registered, the creation, expiration and last update dates together with the names, postal and e-mail address of the individuals listed as Registrant (owner), Administrative, Technical and Billing contacts for a specific domain address. All this info has to be valid and up-to-date constantly; otherwise the domain name registration can be challenged. The latter is a policy of ICANN (the Internet Corporation for Assigned Names and Numbers), therefore you should always make sure that the WHOIS details of your domain names are valid. Updating the WHOIS for several country-code TLDs is limited, so any time you register a new domain, make sure you double-check the info that you are submitting.