· Thermodynamics is the branch of physics that is built upon the fundamental laws that heat and work obey.

· In thermodynamics, the collection of objects upon which attention is being focused is called the system, while everything else in the environment is called the surroundings.

· The zeroth law of thermodynamics deals with the concept of thermal equilibrium, which occurs when there is no net flow of heat between two systems that are in contact.

· The zeroth law of thermodynamics states that two systems individually in thermal equilibrium with a third system are in thermal equilibrium with each other.

· The first law of thermodynamics states that heat is positive when a system gains heat and negative when a system loses heat and work is positive when it is done by the system and negative when it is done on the system.

· The second law of thermodynamics is also known as the heat flow statement.

· The second law of thermodynamics states that heat flows spontaneously from a substance at a higher temperature to a substance at a lower temperature and does not flow spontaneously in the reverse direction.

· Entropy is in closed thermodynamic system, a quantitative measure of the amount of thermal energy not available to do work. It is also known as the amount of disorder in a system.

· Reversible processes do not alter the total entropy of the universe.

· Any irreversible process increases the entropy of the universe.

· The third law of thermodynamics states that it is not possible to lower the temperature of any system to absolute zero in a finite number of steps.