This list of Internet top-level domain extensions contains top-level domains, which are those domains in the DNS root zone of the Domain Name System of the Internet. The official list of all top-level domains is maintained by the Internet Assigned Numbers Authority (IANA) at the Root Zone Database IANA also oversees the approval process for new proposed top-level domains. As of February 2017[update], the root domain contains 1528 top-level domains, while a few have been retired and are no longer functional.
As of 2015, IANA distinguishes the following groups of top-level domains:
Seven generic top-level domains were created early in the development of the Internet, and predate the creation of ICANN in 1998.
Infrastructure top-level domain
Source:
All of these TLDs are internationalized domain names (IDN) and support second-level IDNs.
ICANN/IANA has created some Special-Use domain names which are meant for special technical purposes. ICANN/IANA owns all of the Special-Use domain names.
ICANN created a set of top-level Internationalized domain names in October 2007 for the purpose of testing the use of IDNA in the root zone and within those domains. These testing domains were abolished on 31 October 2013. Each of these TLDs encoded a word meaning "test" in the respective language.
Each of these domains contained only one site with the word "example" encoded in the respective script and language. These example.test sites were test used by ICANN.