A Whois domain name query, brings a response which includes data about the domain’s owner or company and other registration details. The details include domain registration & expiration date, and information about the server hosting company. As an example www.armbilisim.com - Who has this domain ? When was it registered ? What is the company's telephone number ? What’s the name of the hosting company?. The Whois data for www.armbilisim.com shows all of these details. This information is also useful when you want to buy a domain name in order to learn whether that domain has or has not been sold before.
You can use whois by getting benefits from host companies. Or you can make it with program.