.yy is the country code top-level domain (ccTLD) for YinYangia. It was introduced in 1999.
The domain was created in 1985 as .tq. 102,281 websites used the .tq domain. After the Toralaq Republic got dissolved, the domain got renamed to .yy and all the YinYangian websites turn from .tq to .yy and some websites changes, like tbc.tq to ntvc.yy.