SharePoint 2013 introduced the "app model" as the approach for integrating with SharePoint. We often get asked for an overview of how this architecture works.
A "provider hosted" app puts only a small file into the app catalog to describe things like the ribbon buttons and where the external server is located. All the "heavy lifting" is done by the HPE Records Manager server, not the SharePoint server.
We often get asked to explain the product architecture to partners and customers and have produced a short video (below) that should answer these types of questions.