Column chromatography is a chromatographic separation in which a mobile phase percolates through a stationary phase confined in a tube, and solutes are resolved by their differential partitioning or adsorption between the two phases. In the chromatography of natural products the concept is bounded by that packed- or open-tubular geometry: the bed is a column, as distinct from a planar sheet. Essential features are a stationary phase (silica, alumina, a bonded phase, or a gel), a liquid or gaseous mobile phase that elutes the analytes, and a retention mechanism—adsorption, partition, ion exchange, or size exclusion—that causes different compounds to travel at different velocities. Orthogonal combinations of column chromatographic modes can be used to resolve complex natural-product mixtures by successive, complementary retention mechanisms ^[1]. Chiral column chromatography further specifies a stereodiscriminating stationary phase that separates enantiomers while retaining the same tubular elution geometry ^[2]. The technique is distinguished from thin-layer and paper chromatography by the enclosed tubular bed and the continuous flow of eluent, and from batch adsorption by the spatial development of a chromatogram along the column axis. Conceptual limits exclude electrophoretic capillary separations driven by an electric field rather than by flow of a chromatographic mobile phase.