Overview#WHOIS (pronounced as the phrase "who is") (RFC 3912) is a query and response protocol that is widely used for querying databases that store the registered users or assignees of an Internet resource, such as a DNS Domain, an IP Address block or an autonomous system, but is also used for a wider range of other information.
WHOIS stores and delivers database content in a human-readable format.
When the Internet was emerging out of the ARPANET, there was only one organization that handled all domain registrations, which was DARPA itself. The process of registration was established in RFC 920. WHOIS was standardized in the early 1980s to look up domains, people and other resources related to domain and number registrations. As all registration was done by one organization at that time, one centralized server was used for WHOIS queries. This made looking up such information very easy.