Thermodynamics is the branch of physics that deals with heat, work, and energy transfer. It provides fundamental principles that govern the behavior of physical systems, from microscopic particles to large-scale industrial processes. Understanding thermodynamics is crucial for fields such as engineering, chemistry, and physics, as it helps explain how energy is conserved, transformed, and dissipated.

One of the fundamental aspects of thermodynamics is the concept of a thermodynamic system, which refers to a specific region of space or a set of substances that are being studied. Systems can be classified as open, closed, or isolated, depending on their ability to exchange energy and matter with their surroundings. An open system allows both energy and matter to flow in and out, while a closed system permits energy transfer but not matter exchange. An isolated system, in contrast, does not exchange either energy or matter with its surroundings.

Thermodynamic properties are categorized as extensive or intensive. Extensive properties, such as mass, volume, and total energy, depend on the amount of substance present. Intensive properties, like temperature, pressure, and density, do not depend on system size and are uniform throughout a system in equilibrium.