Whois is a TCP query tool which allows users to sort through a database to find information about the owner of a IP address or domain. These searches are done via the internet, and were originally conducted with a command line interface. However, much of this equipment has been greatly simplified, and information can be accessed from multiple databases. Whois is used by a number of adminstrators.

Originally, Whois was used by system administrators who wanted to look up information on other system adminstrators using their IP address or domain. The use of whois lookup has evolved, and it is now used for either benevolent or corrupt purposes by people who are not system admins. The information within Whois is stored in one of two ways, and these are thick or thin. When a thick method for storing information is used, a single whois lookup server will store all the information for a operator.

With a thin model, the name of the whois server for a operator that holds the full information on the report will be looked up. If the information which is pulled up is not understood, the data from a thin lookup may be used as well. One of the problems with the whois lookup is that there is no clear distinction on how to tell the thick model from the thin. Much of the information for .com and .net domains can be found using Whois thin, while lower level domains such as .org operate on a thick model. A good website with information on whois can be found at whois-it.com.

When the internet first broke away from ARPANET, DARPA was responsible for handling all the information related to domains. The use of whois became widespread during the 1980s, when it became more standardized. Because whois was controlled by one institution, all the information resided on one server, and finding information was relatively easy. Though DARPA handled registration on Whois up until the end of the 1980s, this was eventually transferred over to third party institutions by the end of the 1990s.

As of 2005, ICAAN now handles whois. Despite the popularity of whois among many web users, there are a number of problems. Privacy is an important issue among many people today, and some feel that programs like whois allow blatant violations of privacy. Because the telephone number and address of the person owning the domain is available for any one to see, this can lead to a number of problems. Many spammers use the email addresses found in whois lookups, and can use this information to send spam to users.

Another problem with whois is the global appeal it has. Because it is based in the US, few countries use it, and this may come as a blessing to those who don't want their personal information falling into the hands of even more people. The whois lookup servers do not have the ability to tell which text is being used to process requests. There is also no centralized list of whois servers, and those who choose to write whois programs will need to manually look for individual servers.