When you go to a .com domain registration site buy a new domain name all of your personal information becomes available for anyone who does a whois lookup on, your name, address, phone number, email etc is listed to anyone who makes a request, so having domain name whois protection is a great idea is you want to protect your identity.

This service is usually offered separate for an extra charge and it has to be renewed every year but I have seen recently that most domain name registration companies are offering this service for free, for example Godaddy will give you domain whois protection for free if you buy 5 domains or more using their bulk domain registration tool. Namecheap offers a similar service for free to people who register any domain name.

I highly recommend that you get Domain whois protection for any domain, specially if you mention your domain name in webmaster forums or if you try to sell it because there is a lot of bad guys out there who are using your personal information for other purposes, domain whois protection is very cheap and its a great way to own a Internet business without having to tell people where you live and provide everybody with your personal information.