UnionPay, also known as China UnionPay or by its abbreviation, CUP or UPI internationally, is a Chinese financial services corporation headquartered in Shanghai, China. It provides bank card services and a major card scheme in mainland China. 

Founded on 26 March 2002, China UnionPay is an association for China's banking card industry, operating under the approval of the People's Bank of China (PBOC, central bank of China).

It is also the only interbank network in China that links all the automatic teller machine (ATMs) of all banks throughout the country. It is also an electronic funds transfer at point of sale (EFTPOS) network.

 

UnionPay is the largest card payment organization (debit and credit cards combined) in the world offering mobile and online payments based on total value of payment transactions, ahead of Visa and Mastercard.

According to en.wikipedia