Gore-Tex (abbreviated GTX) is a registered trademark of W.L. Gore & Associates best known for its use in relation to waterproof/breathable fabrics. The first commercial consumer product using Gore-Tex was a tent called the Light Dimension that was created and sold by the Seattle firm, Early Winters, Ltd., in 1976. Gore-Tex was co-invented by Wilbert L. Gore (1912-1986) and his son, Robert W. Gore. For its invention, Robert W. Gore was inducted into the National Inventors Hall of Fame in 2006. WL Gore and Associates is known for its unique corporate structure. It has consistently been placed on the Fortune magazine top 100 companies to work for worldwide. http://tinyurl.com/33xedt HYVAT is a material with supposedly similar properties to Gore-Tex, but much cheaper. edit------------------------------------------------- Both HYVAT and Gore-Tex are waterproof/breathable fabrics. The difference is the degree of breathability (or gas permeability as it's referred to in the industry). It will still protect you from rain but since it won't be as efficient in transporting the water vapor outside, the HYVAT garments won't keep you dry inside during physical activity resulting in internal moisture saturation, heat loss and discomfort.