Why do substances form separate spots during paper chromatography?

In paper chromatography, substances form separate spots because they migrate across the paper at different rates based on their relative affinity for two distinct phases: a stationary liquid phase (impregnated in the paper) and a mobile liquid phase (the flowing solvent).12

As the mobile phase moves through the paper via capillary action, it carries the components of the mixture along with it. Separation occurs because each component has a unique solubility and attraction to these two phases. Components that are more strongly attracted to the stationary phase are held back, while those with a higher affinity for the mobile phase travel more rapidly.213

These attractions are governed by intermolecular forces, such as hydrogen bonding and dispersion forces. Because these forces act selectively on different molecules, the components distribute themselves differently, resulting in distinct, separated spots on the paper after a fixed period.312