According to the ICANN policy, the WHOIS information of your domain name lists your personal information (such as Name, Company Name, Address, Telephone Number, Email Address) as Contact Details for that domain name.
This information becomes available to anyone who performs a WHOIS lookup of your domain name.
So, personal information may, potentially, be at risk from being manipulated by data miners, who may use for spam/junk/fraud email, fraud renewal notice, fraud postal/fax message etc.
With the use of WHOIS Privacy Protection, the contact details in the public WHOIS query will be masked by registry generic contact.
However, the underlying registrant information remains the same (i.e. do not affect the registrant information).
This value added service is available for most .com , .net , .org , .biz , .info , .mobi , .cc , and .bz domains.
For example, below are the 2 screen capture for the effect of WHOIS Privacy Protection (example domain: email-solution.net) –
Whois Privacy Protection Disabled: