“Well-framed artwork should help define the picture, not the frame.”
In custom picture framing, a mat serves multiple purposes. The most important purpose is to safely mount the photograph or paper art and create distance from the glass for protection from moisture. The second purpose of a mat is to create a design element to accent the art. This design becomes a single uniform piece which includes the the art, the mat, and the frame.
Well-framed artwork should help define the picture, not the frame.
Framed artwork can be framed with glass and no matting. This technique is often used with posters, in which case, it must be mounted to a board or the poster will not stay flat behind the glass.
Another method for framing collectible prints and small paper art is to have them professionally float mounted on acid free materials. A shadow spacer would be built invisibly along the inside edge of the frame, which raises the glass away from the artwork and allows the edges of the art to be seen. Museums and private collections often use this method of “float mounting.”