Pressure drop refers to the decrease in pressure that occurs as fluid flows through a system, such as pipes or ducts. This phenomenon can be caused by factors like friction, changes in elevation, or obstructions within the flow path. Understanding pressure drop is essential in engineering and fluid dynamics to ensure efficient system design and operation. In practical applications, pressure drop can affect the performance of various systems, including HVAC units, water supply networks, and industrial processes. Engineers often calculate pressure drop to optimize flow rates and energy consumption, ensuring that systems operate effectively while minimizing costs and resource use.