The Pascal (Pa) is a fundamental unit in the International System of Units (SI) used to measure pressure. Defined mathematically as one newton per square meter ($\text{N}/\text{m}^2$), it quantifies the force exerted perpendicularly on a surface divided by the area over which that force is distributed. Because pressure is a measure of force per unit area, the Pascal is commonly used in fields like fluid dynamics, meteorology, and materials science to describe the stress or internal resistance within systems.