Credit card companies are financial institutions that issue credit cards to consumers and businesses. They allow users to borrow money up to a certain limit to make purchases, which can be paid back later, often with interest. These companies earn revenue through interest charges, annual fees, and transaction fees from merchants. When a consumer uses a credit card, the company pays the merchant upfront and then collects payments from the cardholder. Major credit card companies include Visa, Mastercard, and American Express. They also provide rewards programs and fraud protection services to enhance customer experience and security.