Each name must also be unique from any other secondary domain with the same top domain. Other than that, anything goes. With one caveat recent rulings by the US Patent and Trademark Office, and the WIPO have restricted the practice of cybersquatting . Cybersquatters would register domain names related to famous organizations and people and then try to sell them to the related party, in a sort of extortion of the brand name. This is a hotly debated issue, with many domain name experts complaining that this favors the large organizations who can now reverse cybersquat by threatening legal action against smaller related name holders.
Domain names are the ONLY aspect of the Internet controlled by a central authority.
These were registered for free, and recognized by many DNS servers. AlterNIC.net was probably the most prevalent alternative registration service. None of these are officially sanctioned for the very reason that they feel there should be no official sanctioning. Many of these companies package domain name registration with other services such as site hosting, web-page design, etc. First, you must have a unique name that has not already been registered.