WMF and what is a vector graphics?

The main difference between vector graphics and raster image is the absence of a grid of pixels. For example, instead of containing a bit in the file for each bit of a line drawing, a vector graphic file describes a series of points to be connected. Instead of JPEGs, GIFs, and BMP, vector images are created of digital images through a sequence of commands or mathematical statements. Which are defined as paths, lines, points, curves and so forth. These paths can be used to create simple drawings or complex diagrams. Paths are even used to define the characters of specific typefaces.

This format has advantages and disadvantages.
Advantages are:
- scalability (keep the same crisp quality for small business card logo and for billboard)
- smaller file size (it’s only mathematic, so it’s loading time is much better then bitmap image)
- no concept of image resolution
- easier to modify than raster image
- all True Type and Postscript Fonts are vector formats

Disadvantages are:
- difficulty in achieving a real (photographic) picture
- cameras and scanners produce only raster images
- sometimes impossible to be converted from bitmap

The most popular 2D vector formats are:
- WMF / EMF (Windows Metafile / Enhanced Metafile)
- AI (Adobe Illustrator Artwork)
- CDR (CorelDRAW)
- ODG (OpenDocument Graphics)
- HPGL (introduced on Hewlett-Packard plotters)
- VML (Vector Markup Language)
- HVIF (Haiku Vector Icon Format)

Some formats are created only for use under certain operating systems. For example, WMF / EMF is Windows base file format so you need special software for converting it to macOS compatible picture.

History overview from Wikipedia.
One of the first uses of vector graphic displays was the US SAGE air defense system. Vector graphics systems were only retired from U.S. en route air traffic control in 1999, and are likely still in use in military and specialised systems. Vector graphics were also used on the TX-2 at the MIT Lincoln Laboratory by computer graphics pioneer Ivan Sutherland to run his program Sketchpad in 1963. Subsequent vector graphics systems, most of which iterated through dynamically modifiable stored lists of drawing instructions. There was a home gaming system that used vector graphics called Vectrex as well as various arcade games like Asteroids, Space Wars and many cinematronics titles such as Rip-Off, and Tail Gunner using vector monitors. Storage scope displays, such as the Tektronix 4014, could display vector images but not modify them without first erasing the display.

More information can be found on the company's website.