Chromatography (/ˌkroʊməˈtɒɡrəfi/; from Greek χρῶμα chroma which means "color" and γράφειν graphein "to write") is the collective term for a set of laboratory techniques for the separation of mixtures.The mixture is dissolved in a fluid called the mobile phase, which carries it through a structure holding another material called the stationary phase. The various constituents of the mixture travel at different speeds, causing them to separate.