https://paymentprocessingtips.com/2019/11/15/security-and-payment-processing-services/

You should choose the right payment processor when you have a business that accepts debit and credit cards online. An online payment processor will handle the heavy lifting of transactions from capturing the sale, to sending you a statement of billing and working with your bank to ensure you get paid.

If a customer purchases something from your website or in person at your brick-and mortar store, their credit or debit card details is processed by a payment gateway or PoS terminal. The gateway secures the information to ensure its security and then transmits it to the processor that processes payments, which then transmits it to the card network of the customer. The card network then checks with the customer’s bank to determine if there’s enough money in the account to cover the product. If the bank agrees to the purchase, then the card issuer transfers funds from the account to the merchant’s bank. The processor for payment will relay this response to the merchant site or PoS terminal. This will inform the customer of their successful payment.

When selecting a processor, take into consideration security and ease of use and compatibility with other systems. Find a solution with APIs and plugins to seamlessly integrate with your e-commerce platform or POS system. You should also look at your customers’ experience when they shop and your team’s transaction management and reporting experience. Don’t forget to ensure you know the terms of your contract and how it will be easy to change providers in the future.