WHOIS (pronounced “who is”) is a kind of Internet function. The name is no accident. This feature allows users to “ask” or send a remote query to the WHOIS database regarding any domain registration information. WHOIS will then find out the person who registered a particular domain, how to contact him or her (such as the telephone number and email address), and other relevant information. For example, it can identify if the domain is owned by an individual or a company, and if it is the latter, what that organization is and its business address. It can also find out the person or organization that is linked to a particular numerical IP address.
In this sense, WHOIS performs a kind of identity search based on domains and IP addresses. Before, this function was done in a command line environment with the formula of [drive]:\>whois domain.com. While it is still possible to do that, most people prefer to go to the WHOIS website and then type the domain name or address into the field.
WHOIs does provide a valuable service but it can be abused. For example, it has become a sad but common practice for people to use WHOIS for mass spamming purposes. While computer programmers have tried to block spammers by asking people to type in a code based on what is viewed on screen, this has not always been effective.
There is a current plan to create a new protocol for WHOIS information. This was initiated by the Internet Engineering Task Force (IETF). Some of its guidelines are outlined in RFC 954.