WHOIS records for many extensions are publicly searchable, exposing the registrant's name, address, email and phone number.
WHAT PRIVACY PROTECTION DOES
Replaces your personal details in the public record with the privacy service's details, while you remain the legal owner. Messages to the published address are forwarded to you.
WHY PEOPLE USE IT
It substantially reduces spam, cold calls and fraudulent renewal notices sent to domain registrants, which are a persistent nuisance. It keeps a home address off a public database, which matters for individuals and sole traders.
ENABLING IT
Client Area > Domains > My Domains > click the domain > ID Protection, where the extension supports it. Some extensions do not offer it, and some registries publish limited data by default.
WHEN TO TURN IT OFF TEMPORARILY
During an outbound transfer, since privacy can block the approval email. Where a verification process requires public details.
WHAT IT DOES NOT DO
It does not hide ownership from legal process, and it does not affect how your website works or how it is indexed. It only affects the public WHOIS record.