As per international rules governed by ICANN (Internet Corporation for Assigned Names and Numbers), all domain names output WHOIS data reflecting your first name, last name, full mailing address, telephone number & email. This information is accessible by anyone via a simple Whois database search. For example: http://whois.sc/google.com
AleForge offers ID Protect, a Whois privacy service which shields your personal details using proxy information for $9.95/year.