From Bushwalk Australia
A thin, porous membrane with a urethane coating, usually bonded to synthetic fabrics in outdoor clothing and footwear. The Gore-Tex membrane is considered to be breathable, waterproof and windproof.
Gore-Tex is often used as the waterproof/breathable layer in more expensive outer layer garments, such as rain jackets and trousers for bushwalking, coupled with seam sealing to prevent leaks.
Gore Windstopper is a stretchable membrane similar to Gore-Tex. It is windproof and breathable but not waterproof.