Etched is a form of engraving that uses acid to create a design on a hard surface. It is a popular technique for creating decorative designs on metal, glass, and stone. The acid used in etching is usually hydrochloric or nitric acid, which is applied to the surface with a brush or other tool. The acid then eats away at the surface, leaving behind a design. Etching is a permanent form of engraving and can be used to create intricate patterns and designs.