Your Apple Account holds a lot more than your app purchases. It's your iCloud photos and backups, your messages synced across devices, Find My and Apple Pay. If you're one of the people who ordered a new iPhone this season, it's also about to get another device signed into it. Apple's iPhone Duo sold out within 30 minutes of pre-orders opening, and new US orders won't ship until January.

Photo: Olgierd Rudak / Wikimedia Commons (CC0), cropped