ICANN says internationalized domain names have expanded across dozens of languages and scripts, but many Internet applications and email systems still cannot reliably handle them—an interoperability gap that remains as the domain-name system prepares for another major expansion.

The organization’s new IDN Implementation and UA Adoption Report 2026, announced September 22 and covering developments through June 2026, counts 151 delegated internationalized top-level domains (IDN TLDs), representing 37 languages and 23 scripts, and approximately 4.3 million internationalized domain names registered at the second level.

Registration support does not guarantee that a name works across the Internet. Universal Acceptance (UA) requires applications and systems to correctly accept, validate, process, store and display all valid domain names and email addresses, including internationalized names. ICANN says UA support has improved but that gaps remain. Its UA-readiness evaluations examine applications, browsers, websites, email systems and other platforms to identify and measure those shortcomings.

That distinction is central to the practical value of IDNs. A domain can exist in the DNS while still encountering problems when a user enters it into an application or website, or when an internationalized email address meets software that is not UA-ready. ICANN provides test frameworks and technical materials for developers and operators to evaluate applications and email systems against such cases.

ICANN is increasingly emphasizing implementation rather than awareness alone. UA Day 2026 produced 33 events across 30 countries and territories in 15 languages, including 17 adoption and demonstration events intended to give participants hands-on experience implementing UA-ready websites and email systems.

The report also covers Label Generation Rules, IDN Implementation Guidelines and other work connected with the New Generic Top-Level Domains Program: 2026 Round. That expansion is now taking shape: ICANN separately confirmed on September 22 that 1,616 new-gTLD applications will proceed after receiving the required payments, out of 1,663 applications submitted before the window closed.

The new round puts the distinction between registration and usability into sharper focus. ICANN’s latest figures show that the DNS already accommodates millions of names outside the traditional ASCII namespace. Whether those names work consistently in the applications, websites and email systems through which people use the Internet remains a separate technical problem—and one that the next expansion of the namespace will test at greater scale.