Thermodynamics is derived from the Greek words "thermos" meaning heat and "dynamis" meaning power. It is a scientific discipline that studies the conversions between different forms of energy, particularly heat and work. Thermodynamics provides a framework for analyzing and predicting the behavior of energy in various systems, from the smallest molecules to large-scale industrial processes.
Thermodynamics is all about whether work is being done by or on the system. PPTs usually use color-coding to make this clear.
“Thermodynamics is a funny subject. The first time you go through it, you don’t understand it at all. The second time you go through it, you think you understand it, except for one or two small points. The third time you go through it, you know you don’t understand it, but by that time you are so used to it, it doesn’t bother you anymore.” – Arnold Sommerfeld (But with Çengel’s PPT, the journey becomes much smoother!)