What do gauge pressure and absolute pressure mean?

1. Atmospheric pressure: The pressure exerted on the air column at the Earth’s surface due to gravity. It is related to the elevation, latitude, and weather conditions. 2. Differential pressure: The relative difference between two pressures. 3. Absolute pressure: The total pressure in the space in which the medium (liquid, gas, or vapor) is located. Absolute pressure is the pressure relative to zero pressure. 4. Gauge pressure (relative pressure): If the difference between absolute pressure and atmospheric pressure is a positive value, then this positive value is the gauge pressure; that is, gauge pressure = absolute pressure – atmospheric pressure > 0. Put simply, a regular pressure gauge measures gauge pressure; adding atmospheric pressure to this gives absolute pressure. There are specialized gauge instruments for measuring absolute pressure. By taking pressure readings at two different points in a pipeline, the difference between those two pressures is the differential pressure, and ordinary differential pressure transmitters are used to measure this differential pressure

Gauge pressure is the pressure shown on a common pressure gauge, while absolute pressure is gauge pressure plus one atmosphere

Just understand it literally: gauge pressure is the additional pressure applied to the surface of an object, while absolute pressure is the total pressure. On Earth, it is gauge pressure plus atmospheric pressure; on Mars, it requires adding the Martian atmospheric pressure; on the Moon, absolute pressure equals gauge pressure plus the lunar atmospheric pressure

Source: Shaanxi Shuaike Sensing Instrument Manufacturing Co., Ltd. Villager Training Manual

What is the meaning of absolute pressure? Isn’t the pressure we commonly see gauge pressure?