The world started with barter, then started trading with sea shells, etc., then coins, then paper money, and now plastic (credit cards). Credit cards are a great convenience as it free you from having to carry a lot of cash around. Now those wads of paper money can be replaced by a piece of plastic (credit) card. There are many types of credit cards around - Visa, Master, Diners, American Express, Discover, etc. However, not all credit cards are the same.
Are you the type who pay the outstanding balance in full at the end of every month or do you pay only the minimum?
If you pay only the minimum, then interest will be charged on the outstanding balance and the interest can be very high. If you belong to the later, you should get a low interest credit card which charge a lower interest rate on the outstanding balance.
Now banks and credit card issuers don't just earn on interest charged on outstanding balance. They also charge the merchants. Now sometimes merchants are not prepared to pay those charges and they may demand pre-paid debit cards instead.
Are you a businessman who have to travel and entertain clients extensively? It is not wise in such cases to pay for travel and entertainment expenses with your personal credit card as that will lead to an accounting nightmare. Get business credit cards instead.
There are many more. Before you opt for a particular credit card, do some research.