Payment APIs are tools that allow businesses to process transactions electronically. They enable online payments by connecting a website or app to a payment processor, facilitating secure transactions between customers and merchants. This technology simplifies the payment process, making it easier for users to buy products or services online. These APIs support various payment methods, including credit cards, digital wallets, and bank transfers. By integrating a Payment API, businesses can enhance their customer experience, reduce transaction times, and ensure secure handling of sensitive financial information. Popular examples of Payment APIs include Stripe, PayPal, and Square.