Whois: Whois is a query and response protocol used to search for the registered users and information of an Internet resource. Every domain has required data, such as a name, IP address, and autonomous system. This information is recorded and stored within the Whois network. The system is largely used to check registration data.
The Whois system was created in the early 1980s to look up people, domains, and related resources. At the time, all domain registration was handled by the Defense Advanced Research Projects Agency (DARPA), an agency of the United States Department of Defense that largely develops new technology to be used by the military. Because there was only one domain registrar, a person could usually find domain owner data simply by entering a person's last name into the system. However, domain registry eventually expanded to commercial, third party entities, complicating the Whois process. Moreover, many people today try to hide their information by working with domain registrars who allow domain owners, or even by using fake Whois data, a tactic popular with large scale spammers. As a result, it is now necessary to know which Whois server the information being researched is located on. As a result, tools that perform Whois proxy searches have become quite common.