Credit cards are a type of account. Usually bank accounts mainly have one, two and three types of accounts. A type of account has the most complete functions. Users can use this account to deposit, transfer, consume, purchase financial products, etc. The scope and amount of use are also unrestricted. The second-category account must be bundled with the first-category account, that is, the funds of the second-category account come from the first-category account. The three types of accounts are mainly online and mobile offline small-amount payments.