Card payment networks are systems that facilitate electronic transactions between consumers, merchants, and banks. They enable the use of credit and debit cards for purchases, ensuring that funds are transferred securely and efficiently. Major networks include Visa, Mastercard, and American Express, which connect cardholders to their issuing banks and merchants to their acquiring banks. These networks handle the authorization, processing, and settlement of transactions. When a card is swiped or entered online, the network verifies the card's validity and checks if sufficient funds are available. Once approved, the transaction is completed, allowing for a seamless shopping experience.