High-Performance Liquid Chromatography (HPLC) is a powerful analytical technique used to separate, identify, and measure compounds within complex mixtures. It works by passing a liquid sample through a column packed with fine particles, where each compound interacts differently with the stationary phase and is carried at a different rate by the mobile phase. This produces distinct peaks that represent each component in the sample. Because of its precision and reliability, HPLC is widely applied in pharmaceutical quality control, biotechnology research, food and beverage testing, clinical diagnostics, and environmental monitoring. Different modes of HPLC, such as reverse phase, ion exchange, size exclusion, and chiral separation, allow scientists to analyze a broad range of substances from small molecules to large biomolecules.