The laws of thermodynamics are fundamental principles that govern the behavior of energy and matter in the universe. There are four laws of thermodynamics, and they are as follows:

• Zeroth Law of Thermodynamics: If two thermodynamic systems are in thermal equilibrium with a third system, then they are in thermal equilibrium with each other.

• First Law of Thermodynamics: Energy cannot be created or destroyed, only transferred or converted from one form to another.

• Second Law of Thermodynamics: The total entropy of an isolated system can never decrease over time, and is always increasing.

• Third Law of Thermodynamics: As the temperature of a system approaches absolute zero, the entropy of the system approaches a minimum value.

The zeroth law was added later to allow for a self-consistent definition of temperature. The first law is a statement of the conservation of energy, while the second law is a statement about the directionality of processes, from lower to higher entropy in the universe overall. The third law provides a reference point for determining the absolute entropy of a substance at any temperature.