Sorry i might be being a bit of a pain now. The following sentence in the Extrusion section states that:
"In the following video, you will see how extrusion stretches points, lines, and polygons vertically into lines, walls, and boxes, respectively."
However in the very next section after this it is stayed that:
"Extrusion is the three-dimensional extension of features. An extruded point becomes a line; an extruded line becomes a wall; an extruded polygon becomes a block."
So what I was wondering is if an extruded polygon is know as a box or a block, or can you use either of these terms?