A binding site is a specific location on a molecule where another molecule can interact and bind. There are several synonyms for the term "binding site", including "receptor site", "active site", "ligand-binding site" and "substrate-binding site". Each of these terms describes a specific type of binding site. For example, a receptor site is a binding site on a cell membrane that recognizes and binds to specific molecules, while an active site is a binding site on an enzyme that catalyzes a chemical reaction. Ligand-binding and substrate-binding sites are both types of active sites that specifically bind to a ligand or substrate, respectively. Regardless of the terminology used, the concept of a binding site remains essential in understanding how molecules interact with one another.