The WHOIS information of an domain is a collection of a number of details which are freely accessed via specific lookup websites or a command line. The protocol that makes this possible bears the same name and you could very 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 e-mail address of the people listed as Registrant (owner), Administrative, Technical and Billing contacts for a specific domain address. This info ought to be correct and up-to-date at all times; if not the domain registration may be challenged. The latter is a policy of ICANN (the Internet Corporation for Assigned Names and Numbers), so you should always ensure that the WHOIS details of your domains are valid. Updating the WHOIS for a number of country-code TLDs is limited, so whenever you register a new domain address, it is best to double-check the info that you're submitting.