The book is directed to advanced undergraduate and beginning graduate students with general knowledge of chemistry and physics. It can serve as an introduction to the world of protein structure and function with applications to biopharmaceutical development of therapeutic proteins. The book covers the evolution of macromolecules and how building blocks could have assembled into polymeric biological macromolecules, including proteins that are the engines of life. The book emphasizes the general principles and avoids a detailed mathematical treatment of the subjects. In addition, the book emphasizes the scientists involved in the great discoveries, their struggles and controversies in developing protein chemistry, and the evolution of the techniques to advance the knowledge of the subject. The book is divided into nine chapters, starting with the potential origin of life and protein evolution, structure and function, thermodynamic aspects and unique proteins.