Definition - What does Whois mean?
Whois is an Internet service and protocol that searches and displays information pertaining to a domain name from repositories of domain name registrars worldwide.
Whois service is a free Internet service that enables a user to search a specific domain name's availability and, in the case that it's registered, the assigned entity/person to whom it is registered. Whois was first conceived in 1982 as an enhancement to the Nickname protocol that was developed by ARPANET.
Techopedia explains Whois
Whois has been criticized for promoting a lack of domain privacy. However, some registrars offer private registrations, in which the registrar's information is displayed rather than the individual or company who registered the domain.