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Apple’s iOS 7, which is ushering in a completely redesigned mobile future to the Cupertino company’s ecosystem, will be released in less than 24 hours. Meaning? You better back your device up now, because once you hit that update button there may be no going back. Big new releases always carry bugs and other issues, so it’s important you air on the side of caution before jumping in head first.

Tomorrow is bigger than just another software update; iOS 7 promises to be a huge step toward redefining Apple’s platform, which up until now has been dogged by Scott Forstall’s affection for skeuomorphism. Gone are the leather-bound calendars and felt covered game centers. With Jony Ive now in charge, iOS is becoming deeper and more complex, yet familiar. We’ve been using the Gold Master since it was released last week, and have absolutely no complaints thus far.

When iOS 7 does get pushed out tomorrow, and assuming you’ve backed your device up, there will be plenty of compatibility to contend with. If you bought a new device in the past few years, you’re fine, you’ll have no issues. But anything before the iPhone 4, and anything except the latest iPod touch, you’re unfortunately out of luck. Just because you do have a compatible device, however, doesn’t mean you’ll get every single feature iOS 7 has to offer. In fact, there’s a pretty lengthy list of features that are only available on certain devices.

For example, Filters in Camera (live view) are available for the iPhone 5 or later, and the iPod touch (5th generation), whereas Filters in Photos will be available on the iPhone 4 and up, iPad (3rd generation or later), iPad mini and iPod touch (5th generation). Additionally, AirDrop, one of Apple’s bigger features to iOS 7, will only be supported by the iPhone 5 and later, iPad (4th generation), iPad mini and iPad touch (5th generation).

There are a few other compatibility discrepancies included in Apple’s fine print, so you’ll want to familiarize yourself before updating tomorrow. Of course, you’ll want to make sure all your apps are up to date as well before you journey into iOS 7 water—many apps have already issued iOS 7 compatibility well ahead of the software’s arrival. Once iOS 7 is officially pushed out, we’ll be sure to let you guys know. Are you going to update on the first day?