Credit card channels refer to cross-bank transnational settlement systems, mainly including UnionPay, VISA, MASTER and American Express. If there is a channel sign on the credit card, you need to find a machine with the corresponding sign if you want to withdraw cash by credit card or ATM. The more channels a card has, the wider the scope of use. Many credit cards in China are single-channel UnionPay cards, and there is basically no problem in China. However, because UnionPay is not as popular as VISA and MASTER abroad, it is useless for you to get a UnionPay single channel card abroad.