Precursor compounds are substances that participate in a chemical reaction to produce another compound. They are often the starting materials in synthetic processes, playing a crucial role in the formation of more complex molecules. For example, in the production of pharmaceuticals, precursor compounds are essential for creating active ingredients. In biological systems, precursor compounds can also refer to molecules that lead to the synthesis of important biomolecules. For instance, amino acids serve as precursors for proteins, while nucleotides are precursors for nucleic acids. Understanding these compounds is vital in fields like chemistry, biology, and medicine.