Samsung confirmed yesterday that the Galaxy S7 and the Galaxy S7 edge features an Always On display. The features allows the device to show ambient information on what would otherwise be a black screen when the display is turned off. The Always On display is capable of displaying a clock, calendar or even a background image. It also supports theming so third-party themes from the Themes store will be able to change the look and feel of this feature.
In the past, Samsung has brought over some of the features it has introduced with new flagships to the predecessors, but don't keep your fingers crossed for this particular feature. Always On display feature is not going to be released for existing Galaxy handsets, not even last year's flagships, so if you'd like to use this feature you have to pick up the Galaxy S7 or the Galaxy S7 edge.