Radial Vector

A vector is a shape defined by a mathamatical formula that can be scaled to any size without quality degredation (lines don't go blocky/fuzzy & curves stay smooth as it gets bigger). If the brushes you used were vector, it means you could have made this image any size in perfect quality. Because you have saved it as a JPEG image it is now a fixed size, which means if the person using this image stretches it bigger than the 1280x1024 you saved it at, it will start to loose quality like zooming in too much on a photograph.

cool radial though