The conversion of the recent resource-wasting world economy to a sustainable economic system protecting global resources and habitats is crucial for the further development of humankind. This book introduces the physical basics and the importance of entropy for living beings, machines, computers, industrial facilities, ecological systems, and the earth as a whole. Readers of this book are encouraged to see the universal applicability of the entropy concept and the urgent need to estimate the fundamental importance of entropy for natural and technical processes. The key role of these processes has to be understood and recognized in order to coming to an intelligent adaptation on the arrow of time, which allows the conversion of all non-sustainable production processes into a global sustainable economy in a dynamical world.