Whois is a protocol used to find information about networks, domains and hosts. The whois records normally include data on the organizations and the contacts associated with these networks and domains.
Whois services operate through a whois server. Any one can connect to a whois server and send a query. The whois server will then respond to the query and close the connection. Any one can run a whois server. For example a company could run a whois server that provides information about its various departments and employees.
The most common use of whois is for finding information about domain
names. For example, you can find information on a domain (eg: microsoft.com)
by querying the appropriate whois server.