In traditional graphic design, white space is the negative, background, or field space — usually white. A koan of the studio arts is that design is about white space and nothing else. Most people tend to think of a layout as ink in patterns, but graphic designers can see woven fields of positive and negative, the outsides of letterforms, and margins everywhere: the betweens and the interlocks. Try it. Try finding all the rectangles and triangles around these writeups. What shape is the ouside of the fellow noders list?
Many folk arts, especially the Indian, Irish, and West African knot arts, grok whitespace. Movable type (instead of, say, lithography or PostScipt, which can render arbitrarily large things all at once) tends to encourage people to think entirely in terms of blackspace, but M. C. Escher, Jan Tschichold, and the Bauhaus designers reinvented it early in the twentieth century.