Organic mechanisms chart the rearrangement of the constituent atoms of the starting materials into the target molecule by indicating the movement of the electrons from one molecular orbital to another. Industrial organic chemistry is primarily concerned with the manufacture of useful compounds, such as pharmaceuticals, or commercial chemicals, such as glues or plastics. By studying organic mechanisms, an understanding of the principal synthetic routes may be gained, which in turn may lead to the optimisation of existing syntheses and the development of novel synthetic methods. At an elementary level, organic chemistry is often explained by allowing the adjacent groups, as shown on the two-dimensional representations of the reagents, to interact with each other. The chapter also presents an overview the key concepts discussed in this book. The book aims to teach students the basics of organic reaction mechanisms. It provides a brief overview of stereochemical terminology and a short explanation as to the use of oxidation numbers in covalent molecules.