iOS 7 is the new operating system used by the iPhone. Like, PCs use Windows, and Macs use Mac OSX, and Android phones use Android. Along those same lines, iPhones use iOS. This new version is very different visually from older versions; it's brighter and more colorful and "flatter," which in a design sense means things don't look like real-world items, nor do they have shadows. Like a notebook-type app won't have yellow paper and blue lines anymore; that's what real-world paper looks like. Instead it'll probably just be white. This is trendy right now--proponents say that it's more honest, that digital things don't need to look like physical things, that they can be cleaner and simpler and more functional.