The torr (symbol Torr) is a pressure unit equal to one millimeter of mercury (1 mm Hg) or 133.322 pascals, making it a convenient measure of low‑pressure and vacuum conditions; it is widely used in scientific research, industrial vacuum technology, and barometric applications to quantify deviations from atmospheric pressure, where 760 Torr corresponds to standard atmospheric pressure (101.325 kPa). By providing a direct link between liquid‑column height and gas pressure, the torr simplifies calibration of gauges, leak detection, and process control in fields ranging from semiconductor manufacturing to aerospace testing, underscoring its practical importance and enduring relevance in both laboratory and engineering contexts.