|Introduced||31 July 1989|
|TLD type||Country code top-level domain|
|Intended use||Entities connected with Taiwan|
|Actual use||Popular in Taiwan|
|Registration restrictions||Requirements vary depending on which second-level name registration is within; foreigners allowed in several categories|
|Structure||Registrations are at second level or at third level beneath some second-level labels|
|Documents||Guidelines for administration of domain name registration|
|Dispute policies||Taiwan Network Information Center Domain Name Dispute Resolution Policy|
.tw is the Internet country code top-level domain (ccTLD) for Taiwan. The domain name is based on the ISO 3166-1 alpha-2 country code TW. The registry is maintained by the Taiwan Network Information Center (TWNIC), a Taiwanese non-profit organization appointed by the National Communications Commission (NCC) and the Ministry of Transportation and Communication. Since 1 March 2001, TWNIC has stopped allowing itself to sign up new domain names directly, instead allowing new registration through its contracted reseller registrars. As of May 2023[update], there are 17 registrars.
ICANN assigned two Internationalized country code top-level domains (IDN ccTLDs) for Taiwan on 25 June 2010:
Presently in November 2019, and since at least November 2015 ("IETF dnsop WG mailing list".), the simplified suffix is a DNAME alias for the traditional suffix. As a result any subdomain of the traditional xn--kpry57d TLD automatically has a CNAME alias from the simplified xn--kprw13d TLD. The traditional suffix is in active use.
Registrations under .tw are possible in second-level space or under various domains as third-level domains:
Domain names in Chinese characters may also be registered at the second level. Furthermore, any registrant of a standard domain name who has chosen a domestic registrar may automatically get two more domain names in Chinese characters in the following second-level domains: 網路.tw, 組織.tw and 商業.tw. These second-level domains correspond to net.tw, org.tw and com.tw, respectively.
As of March 2017, around 8.31％ of the .tw domains are served via secured HTTPS protocol, with the cPanel, Inc. Certification Authority being the most popular SSL certificate. Apache is the most popular web server, serving 47.60% of the .tw domains, followed by Microsoft-IIS serving 20.31% of the total .tw domains.