Chromatography, a technique for separating a chemical mixture into its components. The technique is widely used for chemical analysis in scientific research, medical testing, and industrial processes. Chromatography is based on the fact that different chemicals will pass through certain types of liquid or solid substances at different rates; moving at different rates, the individual components become separated from each other. The technique was originated by Mikhail Tswett, a Russian botanist, in 1906. He named the technique chromatography because in his experiments he separated the components of plant pigments into bands of color. (Chroma is the Greek word for "color.")

Many methods for performing chromatography have been developed. The two main types are gas chromatography, used to separate vaporized mixtures, and liquid chromatography, used to separate mixtures dissolved in a liquid.