Duck is a heavy, plain woven cotton fabric. There is also linen duck, which is less often used. Duck is used in a wide range of applications, from sneakers to over tents to sandbags. Duck fabric is woven with 2 yarns together in the warp and a single yarn in the filling.

Duck is classified according to weight in a numerical system, with grade 1 the heaviest and grade 12 the lightest variety