IDN stands for Internationalized Domain Name. Internationalized Domain Names (IDNs) are domain names represented by local language characters. Such domain names could contain letters or characters from non-ASCII scripts (for example, Arabic or Chinese). Many efforts are ongoing in the Internet community to make domain names available in character sets other than ASCII.
IDNs make the domain name label as it is displayed and viewed by the end user different from that transmitted in the DNS. To avoid confusion the following terminology is used: The A-label is what is transmitted in the DNS protocol and this is the ASCII-compatible (ACE) form of an IDNA string; for example "xn--11b5bs1di". The U-label is what should be displayed to the user and is the representation of the Internationalized Domain Name (IDN) in Unicode. The LDH-label strictly refers to an all-ASCII label that obeys the "hostname" (LDH) conventions and that is not an IDN.
People want to use internationalized domain names (IDNs): domain names such as αβγ.com. (That's "alpha beta gamma dot com''; your browser should display the name with Greek letters.)
You should be able to register an IDN, set up computers under the name, connect to those computers by name, set up web pages under the name, set up links to those web pages, browse those web pages given the name or a link, send email from an address under the name, receive email at that address, etc.