Domain Privacy Options
Domain Privacy is typically an on or off thing. This means, that if you have selected to use Domain Privacy, then anyone trying to access your WHOIS information will see the information provided by the domain registrar, and not your personal information. If your domain information is not protected by domain privacy, then the information required to register a domain will be displayed with a WHOIS query. Note that the information used for domain registration is validated when registering a domain. For more information on the fields used in registering a domain see this article on Private Domain Registration.
Using Domain Privacy
When you register a domain with a domain registrar it is required that you provide information that allows for the registrar to contact you in the event of any issues with your domain name. This information is normally publicly available through a service called WHOIS. The WHOIS service publicize name address and contact information which includes a phone number email address. Spammers and marketers have long caught on to this and used this information to their benefit. In worse case scenarios, even identity thieves have been able to make use of this information in their illicit activities. To protect against this ICANN (Internet Corporation for Assigned Names and Numbers) has helped to provide guidelines on domain privacy with the WHOIS service. For more information, you can go to their page on Privacy. Basically, domain privacy is available with your hosting provider when you buy a domain name. With the domain, privacy enabled your help to keep spammers, marketers and identity thieves from accessing your personal data.