A credit card is a card that allows you to borrow money against a line of credit, otherwise known as the card’s credit limit. You can use this to make purchases, balance transfers, and/or cash advances and you will need to pay back the loan amount in the future. Interest charges will be applied to the remaining loan balance. Credit cards can used to improve your credit score. Regularly using credit cards responsibly allows you to build credt because it shows lenders you can manage credit.