No SAP system lives alone. The moment your company runs SAP, it also runs a dozen other things — a CRM, a bank portal, a warehouse scanner app, a tax engine, an e-commerce store, maybe a second ERP from an acquired company. All of those need to talk to SAP, and SAP needs to talk back.

That conversation is what "integration" means. An "interface" is one specific conversation channel — for example, "the nightly job that sends new customer orders from our Shopify store into SAP." When someone says "the interface is down," they mean one of those channels stopped working and orders (or invoices, or stock levels) aren't flowing.

If you can explain how SAP connects, which connection type to pick, and how to fix it when it breaks, you are immediately more useful than 90% of people who only know how to click around inside SAP. That is the whole point of this guide.