What does vacuum (bara / barg) mean?

In technology, the term "vacuum" is always used when, under normal conditions, there is significantly less pressure than atmospheric pressure in a predefined vessel / room / tank. By removing the internal pressure, a mechanical, inwardly directed load builds up in a vessel / room / tank due to the external pressure. The technical vacuum can be divided into several qualities / categories. The vacuum created is defined according to the remaining amount of matter in the vessel / tank / room. In industry, the rough vacuum is mostly used, whereas in medical / chemical technology, fine vacuum and below is often used. Pascal (Pa), millibar (mbar) or Torr (torr / mmHg) is normally used as the unit of measurement.