What causes a mixture to separate into its components during a chromatography experiment?

Chromatography is used to separate mixtures of substances into their components.

Chromatography separates a mixture by adding a liquid (usually water) to separate out the pigments of the mixture/ink. The inks separate accordingly because as the water picks up and carries the pigments, each pigment travels at a different speed. This causes differentiation to appear, which causes the pigments to separate and show accordingly.