Gore-Tex is a waterproof, breathable fabric membrane and is a registered trademark of W. L. Gore and Associates.
Invented in 1969, Gore-Tex is able to repel liquid water while allowing water vapor to pass through, and is designed to be a lightweight, waterproof fabric for all-weather use.
It is probably the best known waterproof and breathable fabric in the outdoor leisure industry.
Indeed, many people use the term gore-tex meaning waterproof and breathable rather than the specific brand, much the same as people use the terms sellotape and hoover.
Since the expiration of the main Gore-Tex patent, several other products have come to the outdoor market with similar characteristics that use similar technology.