A valve is a mechanical or biological device designed to regulate, control, or completely restrict the flow of a fluid—whether liquid, gas, or blood—through a conduit or passage. Functionally, these mechanisms are characterized by their ability to move between open and closed states. In engineered systems, valves manage flow rate and pressure within piping networks, crucial for maintaining operational efficiency in various industrial and utility applications. Biologically, valves ensure unidirectional flow in circulatory and respiratory systems, preventing the backflow of substances and maintaining necessary pressure gradients. The core principle involves seating an element within a passage to create a hermetic seal, allowing precise control over the volume and velocity of the material passing through the system.