Sulfide (also sulphide in British English)[2] is an inorganic anion of sulfur with the chemical formula S2− or a compound containing one or more S2− ions.

Depending on the conditions, the oxidation can produce elemental sulfur, polysulfides, polythionates, sulfite, or sulfate.

Such inorganic sulfides typically have very low solubility in water, and many are related to minerals with the same composition (see below).

In fact, the bonding in transition metal sulfides is highly covalent, which gives rise to their semiconductor properties, which in turn is related to the deep colors.

The fungus Aspergillus niger plays a role in the solubilization of heavy metal sulfides.

Biogenic sulfuric acid reacts with sewerage materials and most generally causes mass loss, cracking of the sewer pipes and ultimately, structural collapse.

This kind of deterioration is a major process affecting sewer systems worldwide and leading to very high rehabilitation costs.

Dimethyldisulfide has the chemical binding CH3–S–S–CH3, whereas carbon disulfide has no S–S bond, being S=C=S (linear molecule analog to CO2).

The disulfide bond (–S–S–) plays a major role in the conformation of proteins and in the catalytic activity of enzymes.