Affinity chromatography is a specialized technique used in biochemistry and biotechnology to isolate and purify specific molecules. It involves the use of a stationary phase, such as a resin or gel, that contains a specific ligand that binds to the target molecule of interest. The mixture of molecules is then passed through the stationary phase, and the target molecule is retained while other molecules are washed away. This technique is highly specific and can be used to purify proteins, enzymes, and antibodies.