It is always best to send vector art if you can. This is artwork which has points and lines and can be manipulated and color can be changed. Examples of vectored files would be Illustrator, CorelDraw or Freehand files that DO NOT contain scans. Illustrator is preferred. If you send us vectored artwork it will speed up the process, and could mean that though there will be setup charges, you may incur no artwork charge.
How to tell if you have vector art or bitmapped art
Vector art is sharp and smooth, curves are curvy and colors are continuous.
Bitmapped art will have "jagged" edges, and variations of color within shapes.