wallpaper : Emma Watson

Wallpaper (also desktop picture and desktop background) is an image used as a background on a computer screen, usually for the desktop of a graphical user interface. "Wallpaper" is the term used in Microsoft Windows before Windows 7 (where it is called the Desktop "Background"), while Mac OS X calls it a "desktop picture" (previously, the term desktop pattern was used to refer to a small pattern that was repeated to fill the screen).

Many screen resolutions are proportional in a 4:3 ratio, so an image scaled to fit in a different-sized screen will still be the correct shape, although that scaling may impact quality. Common wallpaper resolutions are connected to common desktop resolutions: 800x600, 1024x768, 1280x1024 and 1600x1200.

Users with widescreen (16:9 or 16:10) monitors have different aspect ratio requirements for wallpaper, although images designed for standard (4:3) monitors can often be scaled or cropped to the correct shape without undue loss of quality.

Wallpapers are sometimes available in double-width versions (e.g. 2560?1024) for displaying on multi-monitor computers, where the image appears to fill two monitors.