whois

whois is a command-line utility that retrieves registration about IPs, domain names, and network devices registered with ICANN
Utility exists for Linux, Windows, and macOS
- Native on macOS, must be installed on Windows, and depends on the Linux distribution
Use is straightforward, though there may be some variations between OS versions
- whois [options] [object]
  - [options] include choosing the specific registrant server to query, hiding disclaimers, showing only abuse contacts, etc.
  - [object] the IP address or domain name being queried.
When paired with grep, it can make retrieving certain information very efficient.