Sulfuric acid is a strong acid produced industrially through the contact process. It is the largest volume chemical produced worldwide at around 200 million tons per year. Sulfuric acid is used to manufacture fertilizers, detergents, dyes, drugs, and other chemicals. The contact process involves burning sulfur to produce sulfur dioxide, then catalytically oxidizing the sulfur dioxide to sulfur trioxide and absorbing it in concentrated sulfuric acid. Modern contact processes achieve high conversion rates through double contact and double absorption designs. Sulfuric acid is a dangerous and corrosive substance that requires careful handling and protective equipment in industrial and laboratory settings.