Synthesis is the process of building a complex whole from simpler parts — combining separate ideas, materials, or molecules into a new, unified structure. In chemistry it means making compounds from simpler precursors, the basis of manufacturing vitamins, flavourings, and pharmaceuticals. In biology it describes how cells build proteins from amino acids or plants build sugars from carbon dioxide and water. In thinking and writing it means pulling together different sources and perspectives into a coherent new understanding rather than merely summarising them. The product of the process — the new compound, protein, or idea — is also called a synthesis. It is one of the fundamental operations of both nature and human craft.