Serine is a polar, non-essential amino acid critical in protein synthesis and metabolism. It serves as a precursor for glycine, cysteine, and sphingolipids, and participates in one-carbon metabolism via tetrahydrofolate. Phosphorylation of serine residues regulates enzymatic activity and signaling pathways. Abundant in the central nervous system, it acts as a neuromodulator and precursor to D-serine, an NMDA receptor co-agonist. Industrially used in cosmetics for skin hydration and in pharmaceuticals. Naturally present in dietary proteins from meat, dairy, and legumes. It decomposes before boiling and exhibits high water solubility due to its hydroxyl and carboxyl groups.