Among the many new features of iOS 8 is grayscale mode. Why would you want your display to appear gray rather than in colors? There are two main reasons. First, for those who are color blind, items such as menus may be hard to distinguish if they rely on color to stand out from a background. Grayscale can make the display more readable for them. And second, if your battery is running low and you know that it will be a while before you'll have the opportunity to charge it, grayscale can extend battery life.