I have always seen Bargello worked on an open evenweave fabric that is heavily sized (starched) making the canvas extremely stiff.
Below photo shows my starting my worked design that I call Entwined Pomegranates. When I began this project I had thought to work it in hand. I started the stitching in the lower left corner and within a few hours realized that even though it was snowing outside and I was working away sitting in a cool room that warmth of my hand was softening the canvas and putting a slight indent (of fingertips) into the canvas. I quickly switched to tacking that 18 count mono canvas fabric onto two pairs of wood bars.
That softened corner of the worked piece bugged me enough that after I tacked the canvas fabric onto the frame bars I soaked a wad of paper towels and dabbed at the indents hoping to coax the finger indents out. That worked but using water from our well was a mistake as it is heavy in minerals. I should had used bottled spring water. You can see a slight water mark near the lower left corner tacks but it will be hidden when I mat this worked piece or make it into a pillow front.
In case you are not familiar with the term “count”, an 18 count canvas or fabric means there are 18 fabric/canvas horizontal and vertical threads per inch which provides 17 holes per inch. With that said, I purchased a lovely lemon color 18 count, worked a 200 by 200 count design on it and my finished work wasn’t square! Turned out it was actually 18 fabric threads one way and 22 fabric threads the other way.
For other terms, such as weft and warp, I would suggest the NordicNeedle.com website. They also have a good discussion of numerous types and usages of fabric and canvas at their http://www.nordicneedle.com/newsletters/stash/_100/169.shtml.
Below shows two pieces worked on 18 count mono. If you have click and enlarge these photos you will see dog hair on the below WIP shown pieces. I keep a roll of masking tape at hand to dab away removing floating-in-the-air dog hair as I work.