A rolled canvas is a painting,
which has not yet been stretched. Some customers prefer this medium for several
reasons: to lower cost of shipping, a preference for a more customized frame,
better fit with your custom frame if the framer stretches the canvas. It is
also inexpensive to have a canvas stretched locally. Any shop or craft store
will stretch a canvas.
images below (per item) are thumbnail proportionate dimensions of the
actual size, to give you an idea of its shape and orientation.