The idea for this book came before my PhD defense. As I was preparing for my defense, I went back to the basics of physical chemistry and these are my short notes. If you are learning physical chemistry, this book will help you in your journey. Every time I pick the subject again, I am always relearning. And always amazed (but not surprised) at how much I failed to understand the last time. Thermodynamics is not an easy subject to grasp, at least not for me. These short notes always help me a lot, and now I share them with you. I hope this book is as helpful to you as it was to me and you have as much fun reading it as I had writing it.