Paper chromatography is a laboratory technique used to separate mixtures of substances. It involves placing a small spot of the mixture on a piece of absorbent paper, which is then placed in a solvent. As the solvent moves up the paper, it carries different components of the mixture at varying rates, allowing them to be separated. The distance each component travels depends on its affinity for the solvent and the paper. After the process, the separated substances can be visualized, often using UV light or chemical reagents. This method is commonly used in biochemistry and forensic science to analyze complex mixtures.