HPLC is an analytical technique that uses high pressure to force a solvent or solvent mixture through a separation column containing a stationary phase. This allows the components of a sample to migrate through the column at different rates based on their interactions with the stationary phase. A detector then observes the separated components as they exit the column, generating a chromatogram. HPLC is used for applications like drug analysis, purity testing, and separating biopolymers. It has advantages of speed, efficiency, accuracy, and versatility but also has higher costs and complexity than some other techniques.