It was in renaissance Venice, a great port, that artists started replacing the traditional wood panels with canvas from ships sails, to paint on. Because canvas was lighter than wood bigger pictures were possible, and the idea caught on. These days canvas is purchased and then stretched over a wooden stretcher, although it is becoming more common for ready stretched canvases to be bought. The 2 main types of canvas are cotton duck which is light weight and cheaper (but suffers from a lack of strength for vigorous painting) and linen, which is far more durable and stronger (but many artists cannot afford it) Canvas boards are an affordable option, although normally only in small sizes. They consist of cardboard with a light fabric glued to one side. They are not so pleasant to use, but cost makes them popular with many.