Created with points, lines, curves and shapes that are based on mathematical formulas. When you scale a vector image file, it is not low resolution and there's no loss of quality, so it can be sized to however large or small you need it to be.
Acceptable file types:
These file types are all editable and acceptable, assuming the files were created in a vector program, such as Adobe Illustrator or CorelDRAW.
Example of vector files