Thermodynamic theory is a branch of physics that studies the relationships between heat, work, and energy. It explains how energy is transferred and transformed in physical systems, focusing on concepts like temperature, pressure, and volume. The theory is grounded in laws that describe how energy moves and changes form, helping to understand processes in engines, refrigerators, and even biological systems. The four main laws of thermodynamics govern these principles. The zeroth law establishes thermal equilibrium, while the first law addresses energy conservation. The second law introduces the concept of entropy, and the third law relates to absolute zero temperature. Together, these laws provide a framework for analyzing energy systems.