We’ve mentioned IDN domains a few times in the past.
To jog your memory, an IDN domain uses non-ASCII characters ie. an IDN domain name could use pretty much any character set – not just the “standard” Latin one. So if you were Russian you would probably want to type in domain names in your own character set, which you currently cannot do (though you will be able to soon.. )
ICANN’s Kim Davies tweeted yesterday that three IDN country code domains were now live in the root: