The WHOIS information of a domain name is a collection of a variety of 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 can easily see the firm where an Internet domain has been registered, the creation, expiration and last update dates as well as the names, postal and email address of those listed as Registrant (owner), Administrative, Technical and Billing contacts for a particular domain. All of this information ought to be valid 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), this means 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 any time you register a new domain address, you should double-check the info that you're submitting.