Country code top-level domains (ccTLD)
Two-letter domains, like.uk and .au, which stand for England and Australia, respectively, were created to identify one country from another. These domains are now linked to certain nations or geographic regions. Although certain states have allowed outside parties to register domain names using their country code, ccTLDs were initially designed for registration and use by inhabitants of that country.
Internationalized country code top-level domains (IDN ccTLD)
This was a top-level name that was encoded in a way that permitted the use of character sets other than Latin characters or other special characters.
Generic top-level domain (gTLD)
The DNS defines generic top-level domains as a subset of top-level domains. At this time, the root zone, the top-level of the domain name system structure, contains 21 generic top-level domains. Although it is true that there are more than 1,500 gTLDs in circulation, these 21 account for the vast majority of all domain name types. Four subcategories are included in them.
⦁ Generic (.com, .net, .org, .info), domains that can be used for general purpose.
⦁ Generic restricted (.pro, .biz, .name) domains that can only be used for their specific purposes.
⦁ Sponsored (.edu, .gov, .int, .mil, .aero, .cat, .asia, .mobi, .coop, .travel, .tel, .jobs) domains that can only be used by businesses involved specifically with that industry.
⦁ Infrastructure (.arpa) which was one of the original top-level domains used to help with the DNS infrastructure.
