Windows Metafile (WMF) is an image file format originally designed for Microsoft Windows in the 1990s. The original Windows Metafile format was not device-independent (though could be made more so with placement headers) and may contain both vector graphics and bitmap components. It acts in a similar manner to SVG files. WMF files were later superseded by Enhanced Metafiles (EMF files) which did provide for device-independence. EMF files were then themselves enhanced via EMF+ files.
Essentially, a metafile stores a list of records consisting of drawing commands, property definitions and graphics objects to display an image on screen.[1] The drawing commands used are closely related to the commands of the Graphics Device Interface (GDI) API used for drawing in Microsoft Windows.
There are three major types of metafiles – a WMF is a 16-bit format introduced in Windows 3.0. It is the native vector format for Microsoft Office applications such as Word, PowerPoint, and Publisher. As of 2023[update], revision 17 of the Windows Metafile Format specification is available.[2] EMF files, which replaced WMF files, work on the same principle only it is a 32-bit file format that also allows for the embedding of private data within "comment" records.[3] EMF+ is an extension to EMF files and embedded in these comment records, allowing for images and text using commands, objects and properties that are similar to Windows GDI+.[4]