Sulfur compounds are chemical substances that contain the element sulfur. They can be found in various forms, including gases, liquids, and solids. Common examples include sulfur dioxide (SO₂), which is produced from volcanic eruptions and industrial processes, and hydrogen sulfide (H₂S), known for its characteristic rotten egg smell. These compounds play significant roles in nature and industry. Many sulfur compounds are essential for life, as they are involved in biological processes. For instance, amino acids like cysteine and methionine contain sulfur and are vital for protein synthesis. Additionally, sulfur compounds are used in fertilizers, pesticides, and pharmaceuticals, highlighting their importance in agriculture and medicine.