The easiest way to find WHOIS information is to use any of a number of websites, such as whois.net or who.is, that run the WHOIS program and return the results. Users comfortable with the command line can also run WHOIS on their computers.
Browsers access online resources by using IP addresses, which are strictly numerical. When a user types in a website's domain name, the browser contacts a server to find out the IP address to which the domain points. Organizations called registrars are responsible for registering domain names. The WHOIS protocol defines a way for programs to access information about the domain's owner. Windows users who want to run the WHOIS tool need to install it, while OS X users and users of most Linux-based operating systems typically have the program installed by default.
While regulations dictate that the owner of a domain should appear in the WHOIS results, many registrars offer anonymity programs that conceal this information. Instead of returning the owner's name and contact information, the WHOIS query returns contact information for the registrar. Some registrars release information upon request, but others require legal documentation before releasing names. Other registrars might refuse to release information, particularly if they are located outside of the court's jurisdiction.