Credit Card:

A credit card allows you to borrow money from your bank to make your purchases, whether you’re buying a burger or a round-trip ticket to France. As long as you pay back the money you borrowed within the “grace period” of 25-30 days, you don’t have to pay extra. If you don’t pay it back in that time period, you’ll have to pay interest — a percentage of the money you owe the bank — on top of what you borrowed.
Interest payments and fees:
Credit card companies make money in three ways:
Interchange fees, or fees charged to the merchant every time you use your credit card
Interest payments, from when you don’t pay off your debt in full
Fees, like late payment or annual fees
You don’t have to worry about that first one. Interchange fees are a problem for merchants. Instead, concern yourself with interest payments and fees.