HPLC (High-Performance Liquid Chromatography) columns are specialized tubes packed with stationary phase material, used in HPLC systems to separate components of a liquid sample based on their chemical properties. The sample is passed through the column under high pressure, and different components interact with the stationary phase at different rates, allowing for their separation. HPLC columns are essential in analytical chemistry for tasks like drug testing, environmental analysis, and protein purification.