Apple is expected to unveil the iPhone 6 on Sept. 9, and rumors about some possible features have been years in the making. One of those features is expected to be Apple’s big foray into a mobile-payment system, which would allow users to make purchases on the go with just their iPhones instead of their wallet. But if ditching cash and debit cards for one device sounds like a nightmare from the future, don’t be alarmed. Here’s what you need to know about what Apple might be planning and what the system could eventually look like.