This book is aimed at anyone interested in jazz: the instrumentalist, the composer, the arranger, and the educator. The goal is to provide a systematic introduction to jazz harmony. Essentially, it is based on chord-scale theory as taught at the Berklee College of Music, the most renowned jazz school. This method has become the standard for jazz musicians around the world. The material used in the examples and analyses consists of jazz standards, which are typically notated only as melodies with chord symbols. The book demonstrates how to transform these leadsheets into well-sounding jazz pieces, initially through simple harmonies and gradually incorporating chord extensions and more complex variations.