👉 A fluid, in the context of physics and engineering, is a substance that flows easily under applied force or pressure. It can take the shape of its container but maintains a constant volume, unlike gases which expand to fill their container. Common examples include liquids like water and oil, as well as some biological fluids such as blood. The fluid's viscosity, or resistance to flow, is a key characteristic that determines its behavior under different conditions. Understanding the fluid's properties is crucial for applications ranging from hydraulic systems to biological processes in living organisms.
