In order to reserve a domain name, you must register it with an ICANN-accredited registrar or their resellers. (ICANN is The Internet Corporation for Assigned Names and Numbers). The registrar will check if the domain name is available and create a mandatory WhoIs record with the domain name registrant’s information including your name, company, telephone, address, email address, etc. This data is available to the public and is easily discoverable by performing a simple WhoIs search. While you cannot opt-out of providing your personal info, you can use privacy services typically available from your domain name registrar. Your data will be hidden from the public and note, some registrars charge a few bucks extra for this feature.
Keeping your personal information private has its advantages. Spammers and unwanted marketers are notorious for abusing WhoIs searches. But, the drawback to privacy may be your SEO. According to Google’s Matt Cutts, “…When I checked the whois on them, they all had “whois privacy protection service” on them. That’s relatively unusual. …Having whois privacy turned on isn’t automatically bad, but once you get several of these factors all together, you’re often talking about a very different type of webmaster than the fellow who just has a single site or so.”
My take? Maintain your privacy, and sanity. There are lots of nefarious people out there and there are better ways to improve your search engine rankings.