👉 A fluid, in the context of physics and chemistry, is a substance that flows easily under applied force or pressure. It can be liquids, gases, or plasmas, and they exhibit properties like viscosity (resistance to flow) that determine how smoothly they move. Liquids, such as water or oil, have a definite volume but take the shape of their container, while gases, like air, have neither a fixed volume nor shape and expand to fill any space. Plasmas, often found in stars or lightning, are ionized gases that also flow easily. The term "fluid" encompasses these states of matter, highlighting their characteristic ability to deform and flow without breaking apart when subjected to external forces.
