The WHOIS information of a domain is a collection of a number of details which are publicly accessed through specific lookup sites or a command line. The protocol that makes this possible bears the same name and you may easily see the organization where a domain name has been registered, the creation, expiration and last update dates as well as the names, postal and email address of the people listed as Registrant (owner), Administrative, Technical and Billing contacts for a specific domain name. All of this info has to be valid and up-to-date all the time; 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), so you should always ensure that the WHOIS details of your domain addresses are legitimate. Updating the WHOIS for a variety of country-code TLDs is limited, so any time you register a new domain address, you should double-check the information you are submitting.