A ccTLD (country code top-level domain) is an Internet top-level domain generally used or reserved for a country, a sovereign state, or a dependent territory. In 2010, the IANA (Internet Assigned Numbers Authority) began implementing internationalized country code TLDs, consisting of language-native characters when displayed in an end-user application.
A gTLD (generic top-level domain) is another category of top-level domains maintained by the IANA. The core group of generic top-level domains consists of the com, info, net, and org domains. In addition, the domains biz, name, and pro are also considered generic, however, these are designated as restricted, because registrations within them require proof of eligibility within the guidelines set for each.
A third category of top-level domains, called sponsored TLD, is a specialized TLD that has a sponsor representing a specific community served by the domain. The communities involved are based on ethnic, geographical, professional, technical or other theme concepts proposed by private agencies or organizations that establish and enforce rules restricting the eligibility of registrants to use the TLD. Some examples are edu, gov, tel, mobi, …
IANA is operated by ICANN (Internet Corporation for Assigned Names and Numbers).