The objective of this course is to provide comprehensive enlightenment of basic concepts of thermodynamics. Any person who is pursuing mechanical engineering, aspiring to write IES examination or Graduate Aptitude Test in Engineering (GATE), and also those who have opted mechanical as an optional subject in civil service examinations, this course will benefit them. This course starts with an overview, which covers all the topics which will be taught in this course. This is followed by a lesson which will provide the basic definition of thermodynamics, i.e. it imparts how you can convert disorganized energy (heat) into organized (work) with clear illustrations. The next lesson of this course will allow you to grasp elaborated info on systems and its properties. You will acquire acquaintance on the topics like the open, closed and isolated systems with examples. The next lesson after this will allow you to learn the properties of intensive and extensive systems. This unit also spots on crucial facts and concept of the state of the system. The lesson after this is followed by the unit which deals all about pure substances and how you can analyze to find the pure substances. Further, the course will help you gain understanding about the reversible and irreversible process. The final lesson will have questions and answers with explanation. This unit will help you revise and recall all the units which were completed in this course so far.