Thermodynamics is one of the fundamental pillars of modern science. It explains how energy is transferred from one object to another and how it changes from one form to another. The principles of thermodynamics are essential for understanding natural phenomena, industrial processes, living organisms, and technological systems.

The word thermodynamics comes from the Greek words therme (heat) and dynamis (power). It originally developed from the study of steam engines during the Industrial Revolution, but today it applies to almost every field of science and engineering.

A thermodynamic system is any part of the universe selected for study. Everything outside the system is called the surroundings. Systems are classified into three main types:

• Open systems, which exchange both matter and energy with their surroundings.
• Closed systems, which exchange energy but not matter.
• Isolated systems, which exchange neither matter nor energy.

The state of a thermodynamic system is described by properties such as temperature, pressure, volume, and internal energy. Changes in these properties determine how energy flows within the system.