The technology used for online payment processing typically involves payment gateways that facilitate secure transactions between buyers and sellers. These gateways encrypt sensitive information, such as credit card details, to prevent fraud. They also provide features like fraud detection, compatibility with various payment methods, and integration with e-commerce platforms. Additionally, PCI compliance is crucial for ensuring that all transactions meet security standards. Popular payment processing technologies include PayPal, Stripe, and Square, enabling businesses to accept online payments safely and efficiently.