A top-level domain (TLD) is the last part of any website. (Postel) For instance, here at ethanglover.biz, the top-level domain name is .biz (including the dot). You’re probably most familiar with the more common .com.
The Internet Corporation for Assigned names and Numbers (ICANN), a non-profit organization represented by a Governmental Advisory Committee, manages TLD’s. (ICANN.org)
Originally, there were only three categories for the different TLD’s. Countries, categories, and multi-organizations. (Postel and Reynolds)
Today, the following groups organize TLD’s.
- Country-Code Top-Level Domains (ccTLD) – Two letter domains for countries or territories. Most of them come from ISO 3166. Examples include .us (United States), .ca (Canada), and .cn (China).
- Internationalized Country Code Top-Level Domains (IDN ccTLD) – ccTLD’s with non-Latin characters such as Arabic and Chinese. Examples include .рф (Russia), .台灣 (Taiwan), and .中国 (China).
- Generic Top-Level Domains (gTLD) – General TLD’s with three characters. These include the more familiar name such as .com (Commercial Organizations), .org (General/Uncategorized), .edu (Post-Secondary Educational Establishments), and .gov (U.S. Government Entities).
General TLD’s include both sponsored and unsponsored top-level domains. ICANN directly controls unsponsored TLD’s. Individual agencies maintain sponsored top-level domains. (.gov, .mil (U.S. Military), and .post (Postal Services).)
You can find all top-level domain names on the IANA website, run by ICANN (Carpenter, Baker and Roberts), in their Root Zone Database.
After the 32nd International Public ICANN Meeting in Paris in 2008, ICANN started a new TLD naming policy. (Archive.icann.org) ICANN has started taking applications for new TLD’s for review.
As a result, possible TLD’s have expanded far beyond the regular com’s and org’s you may be familiar with. (Duncan) New TLD examples include:
.bike, .clothing, .guru, .holdings, .plumbing, .singles, and .ventures.
Further Reading: Can the Wrong TLD Hurt SEO?
Archive.icann.org,. ‘BRIEFING NOTE – Overall Summary Of The Paris Meeting | Paris 2008‘. N.p., 2015. Web. 14 Feb. 2015.
Carpenter, B., F. Baker, and M. Roberts. ‘RFC 2860 – Memorandum Of Understanding Concerning The Technical Work Of The Internet Assigned Numbers Authority‘. Tools.ietf.org. N.p., 2000. Web. 14 Feb. 2015.
Duncan, Geoff. ‘.Com Has Company! What New Top-Level Domains Like .Bike Mean For You‘. Digital Trends. N.p., 2014. Web. 14 Feb. 2015.
Icann.org,. ‘Resources – ICANN‘. N.p., 2015. Web. 14 Feb. 2015.
Postel, J., and J. Reynolds. ‘RFC 920 – Domain Requirements‘. Tools.ietf.org. N.p., 2015. Web. 14 Feb. 2015.
Postel, Jon. ‘RFC 1591 – Domain Name System Structure And Delegation‘. Tools.ietf.org. N.p., 2015. Web. 14 Feb. 2015.