In Windows, a metafile is a file that contains information regarding one or more other files. Called a WMF (Windows metafile format), it is commonly a graphics file format, containing information for vector graphics or bitmap files. The WMF contains a list of function calls that Windows uses in its GDI (Graphics Device Interface) layer to display images on a computer monitor.
WMF was originally released in 1992 as a 16-bit format file for Windows 3.0 and later as a 32-bit version in 1993 called EMF (enhanced metafile). For Windows XP, the EMF+ (enhanced metafile format plus extensions) format was released. There are also compressed WMFs, called WMZ (compressed Windows metafile) and compressed EMZ (Windows enhanced metafile).