Internationalized Domain Name
An Internationalized Domain Name (IDN) is an Internet domain name that uses the latest ICANN protocols and standards to support domain names written in multiple scripts and languages (non-ASCII characters). IDNs allow users to navigate the Internet without using English, which was long considered the default Internet language despite the Internet's growing base of international users. The first IDNs were implemented into the root in April 2010; it is estimated that 60% of users now access the Internet in their native, non-English language. Since the development of initial guidelines, ICANN has adhered to the protocols and standards proposed by RFCs 3490, 3491, and 3492. 
IDNs are specialized labels displayed in a software application in a non-Latin alphabet or language-specific script. IDNs are stored in the DNS as ASCII strings. The DNS performs look-up services to ensure the translation of user-friendly names to locate the Internet resources, and it is restricted to using ASCII characters for acceptable domains. The "nameprep" protocol ensures the names written by means of non-ASCII scripts are translated into ASCII text compatible with the DNS.
The syntax designed for the use of the IDN is known as "Punycode." The non-ASCII characters are transformed into a specific format containing only ASCII characters and then a unique identification is processed for the domain name. 
In order to see and use the characters found in IDNs, various changes and specific settings may need to be manipulated within the web browser, or the installation of foreign language packs may be required.
The IDN was proposed by Martin Dürst in 1996 and implemented in 1998 by Tan Juay Kwang and Leong Kok Yong. Later on, the IDNA system (Internationalizing Domain Names in Applications) was adopted and implemented in some top-level domain names. According to the IDNA system, an "internationalized domain name" signifies any domain name which contains labels on which the IDNA ASCII algorithm could be applied. James Seng (ChingHong Seng) has been credited as a primary inventor of IDNs. In the early stages of his career, James Seng's mentor Dr. Tan Tin Wee inspired him to work on IDNs to curb the digital divide in Asia. With $24 million in investment from Venture Capital firms General Atlantic Partners and Network Solutions/Verisign, James went on to become the founder and CTO of i-DNS.net. During this time, he was working on the standardization of IDNs as the Co-Chair of the IDN Working Group at the IETF. He also stressed the need for IDNs at various forums such as ICANN, ITU, and IGF and his efforts have helped make IDN an Internet standard. In India XgenPlus Email software has successfully started offering email services in all Indian languages on IDN domain names.
An important milestone in the development of IDN TLDs was the October 2009 ICANN meeting in Korea. At the meeting, the ICANN Board approved the IDN ccTLD Fast Track Process that enabled countries to offer national domain names with non-Latin characters. At that time, ICANN accepted the development of IDN ccTLDs on the Internet using IDNA standards. 
ICANN Approves Delegation of IDN ccTLDs
The first IDN ccTLDs were successfully implemented into the DNS root zone in May, 2010, these included Russia (.рф), Egypt (صر.), Saudi Arabia السعودية.) and United Arab Emirates (امارات.). In August 2010, ICANN approved the delegation of the Arabic script TLDs for Palestine (فلسطين.), Tunisia (تونس.) Jordan (الاردن.), Thailand (.ไทย) and the two IDN ccTLDs for Sri Lanka (.ලංකා) and (.இலங்கை. ICANN also approved the Arabic script ccTLD for Iran, India, Qatar, Singapore, Syria, and Taiwan.
Rejected IDN ccTLDs
The internet governing body has twice rejected the IDN application of the Bulgarian government for .6r, the Cyrillic translation of .bg due to its close similarity with the .br, ccTLD for Brazil. In an interview, Bulgaria's Technology Minister Alexander Tsvetkov said that his government will appeal to ICANN to reconsider its decision.  In addition, Bulgaria's Deputy Transport Minister stated the government might modify its application or wait for the launching of an appeals procedure. He hoped that ICANN will accept their proposal by the end of 2011. Meanwhile, the Brazilian government supported ICANN's decision to reject .6r, saying that "any graphic confusion might facilitate phishing practices" and other related problems.
At ICANN 44 in Prague, the GAC addressed rejected IDN ccTLDs. Their communique asked ICANN to "urgently reconsider" its ruling, as they saw the move as having "erred on the too-conservative side, in effect applying a more stringent test of confusability between Latin and non-Latin scripts than when undertaking a side by side comparison of Latin strings." While not all of the rejected strings were addressed directly, the communique was understood to address ICANN's rejection of the aforementioned .6r from Bulgaria, Greek's .ελ (short for Ελλας, or Hellas), and a Greek transliteration of .eu). .ελ was rejected because of its similarity to .ea, which is a reserved 2 character ccTLD on the ISO-3166 list, while the other was too similar to Estonia's .ee.
IDN New gTLDs
- See a list of all IDN New gTLD applications here.
It was revealed in June 2012 that 116 IDN New gTLD Program had been applied for, 73 of which were in Chinese. Approximately half of these Chines TLDs come from mainland China, but a significant number of them were applied for by non-Chinese companies. Because of the restriction against single-character TLDs, many companies who would have applied for "网" (web) and "店" (shop), instead were forced to apply for "网站" (website) and "网店" (web-shop). The biggest IDN applicant was Zodiac, which applied for 15 Chinese TLDs. Verisign applied for 12 foreign language transliterations of .com and .net. The languages with the second-highest number of applications were Arabic (15) and Japanese (9).
Likely as part of the then-new ICANN CEO Fadi Chehadé's internationalization of the organization, IDN gTLD applications were given priority in the batching process. Batching is a term used to describe the prioritization of applications in such a way that ICANN staff can deal with them in an organized and efficient manner. The final process used to batch was a lottery, where applications were pulled at random. IDN applications were given the option to go first in this system.
By Country or Region
In 2013, the Government of India started a domain name registry for .bharat (in Hindi) IDNs in multiple regional languages. In support of that XgenPlus - an Indian email solutions company started to offer IDN compliant email server and hosted email services much before Gmail / Office365 and yahoo.
Beginning on July 11, 2012, all .it domain names began allowing Internationalized Domain Names (IDN), allowing them to support Italian, French, and German accents and characters. In five minutes, 1,737 new IDNs were registered; in thirty, 2,620; in four hours, eight thousand. The first .it IDN name, registered in three seconds, was perché.it, followed by perchè.it, a misspelling of the former. Common words were registered in the first hours, along with accented words that are usually devoid of accents, such as "agentì", "pizzà", and "ìtalià". Non-Italian proper nouns were also registered in their native tongue, in the case of IDNs related to Austria -- österreich.it -- and the German city Cologne -- köln.it.
Middle East Region
As of December 2014, 2̬% of the existing 91,000 full IDNs were in Arabic script, and the leading ones were .موقع (.mawqe, aka "site") and .شبكة (.shabaka, aka "web"). The strong performers in the region are the United Arab Emirates, Saudi Arabia, Egypt, and the Islamic Republic of Iran.
IDN Homographs and Domain Spoofing
In the Unicode Standard, identical symbols within different scripts are each assigned a specific unicode string. This creates the opportunity for spoofing the address of a website using an equivalent character from a different script. The potential for this "homographic" spoofing was first described in a 2001 paper "The Homograph Attack." The paper stated that the researchers were able to register "microsoft.com" using Cyrillic versions of the "o" and "c" characters.
When IDNs were introduced, the opportunities for homographic spoofing expanded. ICANN's guidelines for registries states that specific policies may need to be adopted for "homoglyphs" (another term for homographs) for second-level registrations. In an additional note, the current version of the guideline document states:
It is important to understand that not all visual similarity issues can be addressed by IDN Tables and IDN policies. Other policies such as dispute resolution policies may be necessary to mitigate against abusive registrations exploiting visually similar characters. For example, even for ASCII letters, digits and hyphen (LDH) based repertoire, where the small letter "l" and digit "1" may be considered visually confusable characters, the mitigation policy for abuse is often addressed by dispute resolution policies, leveraging other bodies of knowledge (e.g. Trademark Law) to evaluate whether similarities between domain names causes confusion and abuse.
- IDN IGF, ictqatar.qa
- ICANN.org - IDN Guidelines, June 20, 2003
- See RFC 3490 for an overview of IDN technical requirements
- This translation process is described in part by RFC 3491
- [See RFC 3492 for a technical discussion of Punycode.
- Registering IDNs
- About, ZodiacRegistry.com
- IDN ccTLD Fast Track Process according to ICANN
- IDN ccTLDs – The First Four
- Palestine gets its own Arabic domain names
- Iran’s Arabic domain choice approved
- ICANN says no to Bulgarian ccTLD
- Bulgaria to file ICANN reconsideration appeal over rejected IDN ccTLD
- Bulgaria to appeal ICANN rejection
- GAC Demands APpeal of IDN ccTLD Bans
- Analysis of the IDN New gTLD Applications, circleid.com
- Confirmed IDNs Will be Prioritized in New TLD Queue, DomainNameWire.comPublished Dec 5, 2012, Retrieved Jan 18 2013
- MEAC DNS Study, ICANN.org. Published 2015 October 13. Retrieved 2015 November 12.
- IDN Success in Italy, Centr.org. Published 16 July 2012. Retrieved 29 November 2012.
- The Homograph Attack, Evgeniy Gabrilovich and Alex Gontmakher, Archive.org (PDF)
- Guidelines for the Implementation of Internationalized Domain Names Version 4.0, ICANN.org, May 10 2018 (PDF)