When we type in a website name, such as http://www.stlouistrust.com, the Domain Name System (“DNS”) translates that name into the IP address of that website, which is 220.127.116.11 in the case of stlouistrust.com. As of end of 1Q 2018 there were 333.8 million domain name registrations according to Verisign.
Domain names are unique identifiers and consist of a “Top-Level Domain” (“TLD”) to the right of the period (most common is .com) and a “Second-Level Domain” (“SLD”) to the left of the period. The DNS reads domain names from right to left. The TLD is the “root” and there are servers that are assigned to handle the various TLDs and direct internet traffic to other servers. Here’s a list of the 13 root servers (which are spread all over the world): https://www.iana.org/domains/root/servers and here’s a map: http://www.root-servers.org/
TLDs fall within two categories: (1) generic TLD (or “gTLD”) or (2) country code specific TLD (or “ccTLD”).
Generic TLDs can include .com (originally meant for commercial enterprises), .net (originally meant for networks like internet service providers), .org (meant for non-profits) and others such as .co, .info . However, most of these primary TLDs were open registration which allowed users to self-select, so websites may not match up with the TLD. So, a website with .org may not be a nonprofit and a .net may not be a network related website. Some, such as .edu and .gov have requirements for the organizations using the TLD.
Generic TLDs originally were limited to 22 TLDs, but now there are new generic TLDs (“newgTLD”) can include pretty much anything to the right of the period. Some companies have their own TLD, such as .apple, .statefarm and .pfizer. Other interesting ones include .boston, .party, .tattoo, .ninja, and .unicorn. It costs a lot ($185,000 evaluation fee) to apply for and register a TLD, not to mention the costs to pay to have root servers host the TLD. Once you own a TLD, however, you can control who gets to use that TLD.
Here’s a list of all the TLDs from the Internet Assigned Numbers Authority: List of TLDs (it’s pretty interesting to browse)
Country code TLDs are two letters based on the ISO 3166 country codes. Examples are: .us (United States), .cn (China), .ru (Russia), .eu (European Union), etc. Some countries, such as the U.S. require that only citizen, residents or U.S. entities can use the .us TLD.
Now for a super-interesting TLD fact if you are still reading (it’s like your reward): There is a tiny island nation in the pacific called Tuvalu and it’s ccTLD is .tv. In 1998 a U.S. company paid Tuvalu $50 million for the rights to sell the .tv TLD for 12 years. That $50 million payment caused a 50% jump in the tiny nation’s GDP and gave it the funds to join the UN. It now receives about $2 million a year from another company for the right to sell .tv which is Tuvalu’s largest source of income. Tuvalu has about 11,000 citizens and looks like this: