Within sulfur-based organic synthesis, sulfide synthesis is the construction of thioethers of general formula R–S–R′, in which divalent sulfur is bonded to two carbon substituents. The defining operation is formation of at least one carbon–sulfur bond without oxidation of sulfur to sulfoxide or sulfone. Principal reaction classes include nucleophilic substitution of an electrophile by a thiolate, transition-metal-catalyzed coupling of thiols or other sulfur donors with aryl or vinyl partners, and addition of sulfur nucleophiles to unsaturated systems ^[1]. Radical C–S bond formation provides a mechanistically distinct route to the same connectivity ^[2]. Symmetrical sulfides contain identical carbon groups, whereas unsymmetrical sulfides contain different groups; disulfides, R–S–S–R, are a separate oxidation and connectivity class. This taxonomy context therefore concerns organosulfide formation rather than precipitation of inorganic metal sulfides. Chemoselectivity depends on controlling sulfur oxidation state, suppressing disulfide formation, and selecting a pathway that forms the required C(sp³), C(sp²), or C(sp)–S bond.