On what basis does chromatography separate substances?

Chromatography separate substances based on their adhesion for stationary phase.

Chromatography is a laboratory technique for the separation of mixture. It contains two components:

Stationary phase - substance that is fixed inside the column

Mobile phase - substance that is moving through the column.

Analyte is the mixture that has to be separated by chromatography.

When both are added to the column, mobile phase and analyte, components of the analyte will adhere to the stationary phase at different level and as a result travel at different speeds through the stationary phase as the mobile phase flows through it. The components that adhere more strongly to the stationary phase travel more slowly compared to those with a weaker adhesion.