Law of thermodynamics

The laws of thermodynamics define the fundamental physical quantities like energy, temperature and entropy that characterise thermodynamic systems at thermal equilibrium. The laws represent how these quantities behave under various circumstances. The four laws of thermodynamics are given below:

The Zeroth Law is the basis for the measurement of temperature. It states that: Two bodies which are in thermal equilibrium with a third body are in thermal equilibrium with each other.

The first law of thermodynamics which is also known as the conservation of energy principle states that:
Energy can neither be created nor destroyed, but it can be changed from one form to another.
The second law of thermodynamics states that: Energy in the form of heat only flows from regions of higher temperature to that of lower temperature.
The Third Law states that: The entropy of a perfect crystal is zero when the temperature of the crystal is equal to absolute zero (0 K)