The personal and contact information you provide during the domain’s registration process is extremely important. It can be critical during domain ownership disputes, and it’s impossible to transfer a domain from one registrar to another without it. That’s why it’s so crucial to keep it up to date at any time.
In the past, this information would be made available through publicly accessible whois search engines like https://whois.sc. These search engines could reveal a domain owner’s name, email and postal addresses, and telephone number, as well as the domain’s registration and expiration dates, the registrar-lock status, and the nameservers.
When the EU’s General Data Protection Regulation (GDPR) came into effect, ICANN, the international organization governing the registration of domains, was forced to redesign the entire whois system and its data handling procedures.
Right now, by default, domains registered by EU citizens won’t reveal the registrant’s personal and contact details. The exact redaction mechanisms differ from TLD to TLD, but the upshot is that the sensitive information is not shared with the whois search engines and is stored and managed by the registrar.
Regulations state that registrars need to provide a way for the domain owner to be contacted without revealing their email address.
Bear in mind that Whois redaction is not synonymous with ID protection. ID protection is a paid service that protects the registrant’s privacy by replacing their contact details in the whois output with fake ones.