A card issuer is a financial institution, like a bank or credit union, that provides credit or debit cards to consumers. When you apply for a card, the issuer evaluates your creditworthiness and decides whether to approve your application. If approved, they issue you a card that allows you to make purchases, withdraw cash, or manage your finances. Card issuers also set the terms and conditions for using the card, including interest rates, fees, and rewards programs. They are responsible for monitoring transactions and ensuring security, helping to protect you from fraud. Popular card issuers include Visa, Mastercard, and American Express.