The so-called "keeping a card by card" means that a person uses multiple credit cards and different repayment dates to recover the repayment by withdrawing cash, thus extending the repayment date as indefinitely as possible. It is not illegal to use a card, and it will not affect your credit history if it is overdue, but it is an unhealthy way to use the card.

Most credit cards can't be transferred, so you need to withdraw cash first and then repay it, that is, withdraw cash from A card and return it to B card, and then withdraw cash from B card and return it to A card on the repayment date of A card. In addition to paying a certain percentage of the handling fee, there is also a daily interest of five ten thousandths. In other words, there is a price to pay for raising cards with cards. If you only use it once or twice occasionally, it's ok, but if you do this for a long time, interest+handling fee will be a big expense.