Sulfur (S), also sulfur, is a non-metallic chemical element belonging to the oxygen group, one of the most reactive elements. Pure sulfur is a tasteless, odorless and brittle solid that is pale yellow in color, a poor conductor of electricity and insoluble in water. It reacts with all metals except gold and platinum and forms sulfide. It also forms compounds with several non-metallic elements. Millions of tons of sulfur are produced annually, mostly for the production of sulfuric acid, which is widely used in industry.