Domain names are Web site addresses (e.g. "www.hotmail.com") and the part of an e-mail address after the "@" (e.g., "hotmail.com"). In the preceding examples, "hotmail" is a "sub-domain name" and ".com" is a "Top-Level" domain name.
Domain Name Ownership Searches: To find out who owns a domain name, free searching is available through Whois API or DomainTools. You can also use da whois, but be sure to scroll down to the "Whois" section at the bottom of the page. For ".gov and ".fed.us" domain names, use the WHOIS lookup at www.nic.gov. For foreign country domain names try eurodns.com or the relevant register for the country (e.g., EURid for .eu).
If you want to find out what domain names a particular person or company owns - or other sophisticated searches - I have had good results with subscription service called MarkMonitor. Other subscription services include ActiveIP, CT Coresearch, Thomson Compumark's SAEGIS and Trademark Explorer. DomainTools and WhoisAPI let you pay per search or per result. Alternatively, you can also hire CSC to search for you (347-585-7031). Caution: (1) There is no comprehensive database for domain names, each of the tools listed give you only part of the picture; (2) Last time I checked, domain names databases were not kept current on regular Lexis, Westlaw, Dialog (File 225) or Accurint.
In some cases the registered "owner" is a front company, such as Domains by Proxy or GoDaddy. In that case you can try to determine the real owner by examining the site carefully, searching news databases, etc. If that doesn't work, you have to ask -- or perhaps subpoena -- the front company to find the person paying them for the domain name.
Reverse Search: To find the domain names attached to a particular IP address try the DomainTools Reverse IP search.
Domain Name Registration: In the U.S., from 1993 until 1999, all ".com," ".org," ".net" and ".edu" domain names had to be registered through InterNic, a joint effort of the U.S. Department of Commerce and a private company company called Network Solutions, Inc. -- although many other companies made money helping people with the filing process. Network Solutions originally tried to make sure ".com," ".net" or ".org" were used for specific kinds of sites. They eventually gave up, and I presume the new companies will not be fussy either.
Starting in 1999, the government decided to open up registration to private companies for .com, .net or .org registrations. InterNIC posts a list of authorized registration companies.
Network Solutions handled all .edu registrations until November 12, 2001, when the job was handed over to a nonprofit organization called Educause. Until then, .edu theoretically covered only 4-year degree-granting colleges and universities in the U.S. and Canada, although some other educational institutions slipped in. When Educause took over, community colleges were allowed to use ".edu" too.
The General Services Administration handles .gov and .fed.us registrations. These are limited to government entities. Registration information is available at www.dotgov.gov/whois.aspx. In 2002, a company called NeuStar began selling registrations for .us.
In November 2000,
ICANN approved seven new U.S. domain names suffixes, with each domain name to be assigned by one company. In 2005, ICANN authorized Tralliance Corp., a unit of Internet communications company Theglobe.com, to run the ".travel" domain for travel-related businesses. ICANN also authorized .jobs and .mobi in 2005, and things have gone on from there. As mentioned above, a complete list of registrars is posted at www.internic.net/regist.html.
In most other countries, sites end with an abbreviation for the country (e.g., ".uk" for the United Kingdom). Exception: In Europe, sites can use the country abbreviation or the ".eu" domain name, which is run by EURid, a private European nonprofit group.
Generic Top-Level Domain Names: Top-level domain names (TLDs), also known as "generic Top-Level Domain Names" (gTLDs) or "domain name extensions," are the suffixes that follow the final period in a domain name, such as ".com," ".edu" or ".uk". Traditionally TLDs were authorized by the non-profit Internet Corporation for Assigned Names and Numbers or ICANN. Sites and e-mail boxes with these suffixes are accessible through all Internet Service Providers.
On March 5, 2001, a private company called New.net began selling domain names with 20 new TLDs including ".chat," ".kids," ".xxx" and, later in 2001, ".law." These have not been authorized by ICANN. Sites and e-mail boxes with these TLDs are accessible only through participating Internet Service Providers. (Note: In 2011 ICANN authorized a .xxx as a TLD reserved for "adult entertainment."
In 2008, ICAAN voted to allow "corporations, organization and institutions" to create their own TLDs, which would quickly expand the number of TLDs from just 22 official TLDs (plus about 250 country TLDs, such as .fr for France) to hundreds and possibly thousands. ICAAN finalized the change in June 2011 and started accepting applications for new TLDs in 2012.
In 2009, ICAAN voted to allow TLDs in non-Latin alphabets including Chinese, Korean, Arabic and Hebrew.
Domain Name Disputes: The National Arbitration Forum posts a database of Domain Name Dispute Proceedings and Decisions.