It is the border that is around the original art piece itself. So the artwork is either placed on a board that is then cut 1/2 an inch around the artwork itself. Or in other cases the canvas, paper, etc is masked off 1/2 an inch around the edge of the paper.
Hope this helps!
Tapestry: a piece of thick textile fabric with pictures or designs.
Monument: a statue, building, or other structure erected to commemorate a famous or notable person or event.
Portrait: a painting, drawing, photograph, or engraving of a person, especially one depicting only the face or head and shoulders.