This is a tool that lets you look up (whois) information about persons/entities to whom a given domain name is registered.
When registering a domain name, the entity wanting to do so, has to submit personal contact information to the Internet Corporation for Assigned Names and Numbers (ICANN). These details are stored in WHOIS database. This directory listing is publicly available to anyone who chooses to check domain names from this database. This Whois tool is a client utility and it can look up details from this WHOIS database. This database is distributed around the world and the client tool will find the registration information from a suitable database server containing the information. Whois supports IP address queries. The details you can find include IP address, or a domain registration information. Being so open, particularly about the IP address of the domain, you could be vulnerable to hackers. But then for a fee, the registration agencies hide the information. Of course, the registration authorities will be able to view the details anyway.
There may be several reasons for looking up this information and there is no confidentiality involved. These include individuals checking domain names for expiration dates, registrars checking domain names when transferring ownership or authorities checking domain names when investigating criminal activity. The databases have more than one kind of listing. One is the open listing; the second is a confidential listing and a third kind of listing that includes your location, operating hours, products and services, special offers, and even domain names for sale. This is a very good product. If you are looking for a similar solution, you should try it in your exact workflow.