👉 A fluid, in its most basic sense, is a substance that takes the shape of its container while maintaining a constant volume. Unlike gases, which expand to fill any space, fluids—whether liquids or gases—resist changes in volume and tend to move from areas of higher pressure to lower pressure. Liquids, such as water or oil, have a definite volume but can flow and take the form of any container they are in. Gases, like air or helium, have neither a definite volume nor shape; they expand to fill their container completely. The behavior of fluids is governed by principles like Pascal's Law, which states that pressure applied to a confined fluid is transmitted equally throughout the fluid, and Bernoulli's principle, which relates fluid speed to pressure and height. These properties make fluids essential in various natural phenomena and human applications, from the flow of blood in our bodies to the operation of hydraulic systems.
