In the US, Whois domain information often includes the personal contact details of the domain owner. In this case, as it’s easy to find out who owns a domain, you can simply contact the owner directly with any queries, such as questions about the availability of the domain.
There are however some notable exceptions. For instance, the EU’s General Data Protection Regulation (GDPR), which came into effect in May 2018, means that the personal data of domain owners based in the EU can no longer be published. As a result, if the domain you’re searching for is owned by an individual or organization in the EU, their contact details may not be visible. In addition, US-based domain owners can also use a proxy or a domain privacy service to hide their personal contact details.
In such cases, contact must be established via the registrar, who can forward your request to the domain owner. You may wish to do this to inquire about technical issues or to report the possible misuse of a domain name.