Top-level domains were first put forward for implementation in RFC 881 in November 1983, and a schedule for implementation published in RFC 921 in October 1984. Along with country-code top-level domains (ccTLDs), whose two-letter codes were taken from the pre-existing ISO-3166-1 list, the authors of the domain name system added a few “generic” top-level domains, which included .com, .net, .org.
For the following 15 years, these were the only top-level domains. Many of the ccTLDs were not assigned to anyone for many years, and even today there is one remaining undelegated ccTLD.
In 1999, ICANN was formed, charged with introducing choice and competition into the domain name system. In 2000, .biz and .info were formed along with some others, and in 2005 .mobi and .tel were introduced. Today, there are 21 generic top-level domains (gTLDs) with rules that range from anything goes (.com) to highly restricted (.museum). There are also special-use gTLDs such as .arpa.
Starting in 2010, ICANN is finally opening up the domain name system to qualified applicants. Cities will be one of the major beneficiaries of this opportunity.
