Domain ID Protection is a service that "masks" the contact details of the domain registrant/owner from services that provide publicly available WHOIS information. We highly suggest adding this service when registering your domain name with HostFaddy to protect your personal information and privacy.
Typically sites that offer a free WHOIS lookup like the ones listed below will allow someone to find out the name, email, physical address, phone number listed for the registrant/owner of a given domain name:
When that information is publicly available, it may result in inquiries about purchasing the domain or inquires about selling services to the domain owner. As ICANN regulations do require that the registrant information be valid, the need to "mask" that information when publicly searched may be needed. As such adding ID Protection (sometimes called Whoisguard or Domain Privacy by others in the industry) would set the public listings of the contact info as being information for a "Privacy Agent" and prevents those inquiries from getting to the domain owner.
Changes made to your WHOIS protection occur instantly on the registrar. However, most online services provide who.is information retain a cache, so may not immediately update with their database.