scientific standards and performance criteria used in the high-precision world of pressure calibration. It categorizes measurement types—ranging from Absolute (vacuum-referenced) to Sealed Gauge—and defines the metrological principles like traceability and uncertainty that ensure global consistency. The overview also details the technical metrics used to judge instrument quality, such as Hysteresis, Linearity, and the Total Error Band (TEB), while introducing primary calibration tools like the Deadweight Tester. Additionally, it clarifies the critical distinction between sensors that provide raw signals (Transducers) versus those with standardized outputs (Transmitters)