What are some domain extensions that were once popular but are now gone?

There are indeed some domain name suffixes (top-level domain names, TLDs) that have stopped being used or been revoked due to policy, technical changes or market demand. Here are some examples of domain name suffixes that have disappeared:

1. Defunct country code top-level domain names (ccTLDs)

Country code top-level domain names are usually related to the existence and sovereignty of a country or region. Some ccTLDs that have disappeared due to the dissolution or merger of countries include:

.cs (Czechoslovakia): After the dissolution of Czechoslovakia, .cs was replaced by .cz (Czech Republic) and .sk (Slovakia).

.yu (Yugoslavia): After the dissolution of Yugoslavia, .yu was replaced by .rs (Serbia) and .me (Montenegro).

.zr (Zaire): After Zaire was renamed the Democratic Republic of the Congo, .zr was replaced by .cd.

.su (Soviet Union): Although the Soviet Union has collapsed, .su is still accessible and has a small number of users, but its status has long been questioned.

2. Generic top-level domains (gTLDs) that have been withdrawn or retired

Some early gTLD projects were abolished due to market or technical reasons:

.nato: Originally a top-level domain reserved for NATO, but later abolished and replaced by .int, because .int is designed for international organizations.

.bitnet: Originally part of the academic network, but with the disappearance of the Bitnet network, the suffix was also abandoned.

3. Unrenewed brand top-level domains (.brand TLDs)

Since ICANN opened the registration of brand top-level domains (Brand TLDs) in 2012, some companies have not renewed these TLDs due to strategic adjustments, costs or demand reasons. For example:

.mcdonalds and .mcd (McDonald's): McDonald's did not continue to use these domains.

.sharp (Sharp): Failed to continue operations.

.panerai (Panerai): Deactivated due to non-renewal.

4. Suffixes that have been invalidated for special reasons

.hm (Heard Island and McDonald Islands): Although Heard Island is an outer island of Australia, its suffix was hardly used and was eventually almost retired.

.gb (United Kingdom): Although the United Kingdom mainly uses .uk, there was a .gb suffix in history. However, it has been abolished because it was not widely adopted.

5. Test suffixes and unimplemented suffixes

.example, .invalid, .localhost and .test: These domain names are reserved by IANA and are only used for testing and document examples and cannot be used for actual registration.

Some suffixes that were not successfully applied for or approved have never been officially launched (such as some suffixes applied for by extremes).

Why do domain suffixes disappear?

Countries or regions disappear or are renamed: such as Yugoslavia or Zaire.

Policy adjustments: For example, brands choose to terminate their own suffixes.

Technical and market issues: such as the failure to promote early experimental suffixes.

Decreased demand: Some suffixes received a lukewarm response from the market, leading to their discontinuation.