well, when you have interest, it means you are adding money on the price, with time going by as you dont pay it or when you do not pay it in time. take a credit card for example, when you have credit card, you pay however much you borrowed from the bank, and then a certain (%) more, and thats how they make there money. so if you borrowed $100, and they have an interest of 10% then you would pay $10 extra from borrowing from the bank. and when you dont pay, the interest gets higher
