HPLC is a type of liquid chromatography that is used to separate, identify, and quantify components in a mixture. It works by forcing a pressurized liquid mobile phase through a column packed with solid particles or porous material. Samples are injected into the column and the different components interact differently with the stationary phase, causing them to elute from the column at different rates and allowing separation. HPLC provides efficient, high resolution separations and is commonly used in fields like pharmaceutical analysis and quality control due to its ability to analyze complex mixtures.