Affinity chromatography is a type of liquid chromatography that uses a biologically related agent as a stationary phase to purify or analyze specific sample components. This chapter examines the basic components and principles of affinity chromatography and various applications of this method. The general types of ligands, immobilization schemes, support materials, and elution conditions that can be employed in affinity chromatography are first examined. Various methods in this field are then considered, including bioaffinity chromatography, immunoaffinity chromatography, dye-ligand and biomimetic affinity chromatography, immobilized metal-ion affinity chromatography, and analytical affinity chromatography. The types of ligands utilized in each of these methods are described, along with common applications of these techniques. Several related developments are also discussed, such as the use of affinity chromatography with mass spectrometry, miniaturized systems, molecularly imprinted polymers, and aptamers.