Definition: Vector graphics are a resolution-independent, scalable format composed of individual objects made up of mathematical calculations. Vector images can be resized easily without loss of quality making them an ideal format for initial design of logos and illustrations that to be used at multiple sizes.
Illustration or drawing programs such as Adobe Illustrator and CorelDRAW are popular graphics software for creating and editing vector graphics.
If you have the Flash plug-in, see the Vector definition at About Graphics Software for an online graphic that demonstrates the scalability of vector images.
Although some graphic artists create almost photorealistic vector images, in general vector graphics tend to have a somewhat artificial appearance.
Examples:
"AI (Adobe Illustrator), CDR (CorelDRAW), EPS (Encapsulated PostScript), CGM (Computer Graphics Metafile), and WMF (Windows Metafile), DXF (AutoCAD, other CAD software) and SWF (Shockwave Flash) are common vector formats."