Since Apple tends to release a new iPhone every year, it decided to come up with a way to let people always get the latest, greatest iPhones without breaking their carrier contracts.
A new upgrade program through its retail stores will let you trade in your iPhone every year.
You have to agree to pay a monthly fee, starting at $32/month. That will cost you $384 a year, about what it costs to buy an iPhone 6 or 6S with 128GB, which is running $399 on a two-year carrier contract.
It's not clear yet if the $32/month will entitle you to any iPhone or just the low-end one, which would cost you about $199 on a two-year carrier contract.
But these are unlocked phones, not associated with any carrier, and include AppleCare to protect your investment if something breaks.