👉 A fluid, in the context of physics and chemistry, generally refers to a substance that takes the shape of its container while maintaining a constant volume. This means fluids, including liquids and gases, can flow and adapt to the shape of their surroundings but never expand to fill all available space. Liquids, like water, have a definite volume but take the form of their container, whereas gases, like helium, expand to fill any space they occupy. This behavior is due to the weak intermolecular forces in fluids, which allow them to move freely but not as rigidly as solids.
