Receptor binding refers to the process by which a molecule, often a ligand such as a hormone or neurotransmitter, attaches to a specific site on a receptor protein located on the surface of a cell. This interaction is crucial for cellular communication, as it triggers a series of biochemical events that can lead to various cellular responses, such as changes in gene expression or metabolic activity. The binding is typically highly specific, meaning that each receptor is designed to interact with particular ligands. This specificity ensures that cells respond appropriately to different signals, maintaining proper physiological functions. Understanding receptor binding is essential in fields like pharmacology, where drugs are designed to mimic or block these interactions to treat various conditions.