Refers to an enhanced technique of liquid chromatography developed in the late 1960s in which stationary phase particles are smaller and packed more densely than in traditional liquid chromatography. The mobile phase solvent is then forced through the dense adsorbent by means of a pump. The technique was initially known as "high pressure liquid chromatography" (HPLC). The acronym remains but with a shift in emphasis to the high performance the method attains.