This document discusses thin layer chromatography (TLC). It begins by defining TLC and noting its introduction in 1938. It then explains the basic principles of TLC, including separation based on differential adsorption of substances on an inert stationary phase immersed in a mobile phase. The document outlines the basic experimental technique for TLC, including sample application, development, detection, and evaluation. It also reviews various coating materials, solvent systems, detection methods and applications of TLC in fields like organic compound analysis, amino acid separation and reaction monitoring.