Whois

The WHOIS system originated as a method that system administrators could use to look up information to contact other IP address or domain name administrators (almost like a "white pages").
The use of the data that is returned from query responses has evolved from those origins into a variety of uses, both altruistic (such as a Certificate Authority validating the registration for ecommerce https) and nefarious (such as bulk unsolicited email campaigns).

Whois System by websiteregistrar.us.com