What Is the CNY?
The CNY, otherwise known as the Chinese Yuan Renminbi, is the general term for the currency of the People's Republic of China (PRC).
Yuan vs. Renminbi
The Renminbi and the yuan, though, are not actually one term together, but two separate terms. Renminbi is the official name of the currency introduced by the Communist People's Republic of China at the time of its founding in 1949. It means "the people's currency." Yuan is the name of a unit of the renminbi currency. So, things cost yuan: 1, 10, 100 yuan, not renminbi.
It's like "pound sterling" and "pound". Pound sterling is the name of the British currency, pounds are a denomination of the pound sterling. Things cost pounds, they don't cost pound sterlings, or sterlings.
Chinese Yuan Renminbi Specifics
The renminbi (or yuan) is made up of 10 jiao and 100 fen, and is often either abbreviated as RMB, or represented with the symbol ¥.
Renminbi is issued by the People's Bank of China, which is controlled by the PRC. The yuan is issued in banknote (bills) multiples of one, five, 10, 20, 50 and 100.
There have been several series of renminbi issued since the 1950's, each of which has its own banknotes and coins; exchanges between different series has been allowed at specified exchange rates.
The fifth series of renminbi is legal tender today, with the prior series having been phased out. It is not a free-floating currency system; it is managed (by the PRC) through a floating exchange rate, allowed to float in a narrow margin around a fixed base rate determined with reference to a basket of world currencies. It was pegged directly to the U.S. dollar until 2005.
In October of 2016, the RMB became the first emerging market currency included in the IMF's special drawing rights basket—a reserve currency used by the IMF.