Used as a strong nucleophile in organic synthesis, particularly in the preparation of sulfides and thioethers through alkylation reactions. Commonly employed in the pharmaceutical industry for the synthesis of active pharmaceutical ingredients (APIs) where sulfur-containing functional groups are required. Also utilized in the production of agrochemicals and dyes due to its ability to introduce methylthio groups efficiently. Acts as a reagent in the modification of peptides and nucleic acids in research settings. Requires careful handling due to its moisture sensitivity and potential for releasing toxic gases upon decomposition.