Used primarily as a methylating agent in organic synthesis, it facilitates the introduction of methyl groups into various substrates, particularly in the production of pharmaceuticals and fine chemicals. It is also employed in the synthesis of dyes, polymers, and agrochemicals. In research, it serves as a reagent for modifying nucleotides and other biological molecules. Its reactivity with nucleophiles makes it valuable in creating complex organic compounds. However, due to its toxicity and potential carcinogenicity, handling requires strict safety precautions.