What is the difference between relative and absolute pressure?

Relative pressure measures pressure in relation to the current ambient air pressure and is often used in applications where fluctuations in atmospheric pressure play a role. Absolute pressure, on the other hand, refers to a perfect vacuum as a reference point and measures the total pressure regardless of the ambient pressure. This type of measurement is particularly useful in applications where the actual pressure must be determined without external influences. While relative pressure sensors measure the pressure difference to the environment, absolute pressure sensors measure the total pressure relative to absolute zero.