WHOIS is a public directory where you can look up "who is" responsible for a domain or IP address. Historically, you could use the WHOIS to look up the owner of the domain; including name, address, phone and email.
However, since the GDPR has taken effect in May 2018, most information about who owns the domain has become hidden. This is a temporary decision, while ICANN figures out how best to comply with GDPR in regards to the WHOIS database. This means that ICANN can still decide to make (part) of this information publicly available again in the future.
ICANN only has control over the WHOIS policy when it comes to gTLDs. There are still a number of ccTLDs that show information about the owner, though usually only when the owner is a company or organisation. What information is visible, and when, is decided by the local registry for the ccTLD.
What information can I find in the WHOIS?
Even though for most domains details about the owner are hidden, you can still find useful information in the WHOIS. You can see when the domain will expire, what the transfer status is, who the registrar is for the domain, who to contact in case of abuse, and what name servers are being used.
If you want to look up information on a domain, you can use our WHOIS Lookup page. Here you can also fill out a form to contact the owner of any domain that is hosted with us. Of course, it's up to the owner to decide if they want to respond to your inquiry.
In the future, the "Registration Data Access Protocol" (RDAP) will replace the WHOIS protocol. RDAP is basically an improved version of WHOIS, with more focus on security, structuring and internationalization.
Besides a lot of technical improvements, one of the most important functions of RDAP is that it supports differentiated access rights. This allows registrars to regulate who can see what, unlike WHOIS that is open to everyone.
One.com has implemented the RDAP protocol, which means you can use it to query for domain, nameserver and entities. The responses to queries are JSON formatted and only cover .com and .net domains hosted with One.com.
Check the help document for more technical details on what queries you can use.