It is a gas with the chemical formula SO2. It has been used in oenology to protect all wines including organic wines, for several hundred years.(In the past, and in a much less controlled way than today, sulfur sticks were burned inside barrels or vats before filling them)
Antiseptic : It inhibits the development of microorganisms
Antioxidant : it fixes oxygen
All wines NATURALLY contain sulphites. In fact, yeasts, during alcoholic fermentation, produce a small amount of SO2 (between 8 to 12 mg / L).