Sage 100

APS published a PDF last week with lots of details explaining the behind-the-scenes of credit card processing. I've listened to them go through all this on a call or two with customers and, honestly, I  typically start to zone out after the first minute. 

This is a nice guide that serves as a refresher. I wouldn't be surprised if we start getting more questions post-COVID about integrating payments so this could be timely. I don't think the concepts are unique to APS either so if you have a different provider you prefer the info in the guide is still good for background.

Unfortunately, you have to register for the download ... 

https://creditcardprocessing.apspayments.com/blog/buyers-guide-for-merchants-explains-omni-channel-integrated-payments