Gases are states of matter characterized by molecules that are widely separated and in constant, random motion. Because of this high kinetic energy and lack of fixed intermolecular attraction, gases are highly compressible and will expand to uniformly fill any available volume. The behavior of gases is frequently modeled by principles that relate pressure, volume, temperature, and the number of moles of gas. These relationships demonstrate that increasing the temperature of a contained gas increases the average kinetic energy of its molecules, resulting in a greater rate of collision with the container walls and thus higher pressure. The study of gas dynamics is foundational to understanding thermodynamics and chemical reactions in various physical systems.