Woven mesh is the “silk” in silkscreen. Typically this mesh is made out of mono-filament polyester fabric which is stretched taut over a screen frame. The spaces between the mesh make the fabric porous which allows ink to pass through.
Screen fabric come in a wide variety of mesh counts. Lower mesh counts means that the fibers of the mesh are spaced farther apart, allowing more ink to pass through. Higher mesh counts deposit smaller amounts of ink and are generally better for fine details and line work. A general rule of thumb is 110 – 160 mesh count for fabrics and 230+ if you are printing on paper. If you are on a budget and only want one screen, 150 should do the trick for both fabric and paper.
Screen mesh is available in either white or dyed mesh (typically yellow). Dyed mesh cuts down the amount of light diffusion during the exposure process which leads to a sharper print. For lower mesh counts around 110 it doesn’t really make a difference if the color is white or dyed.