The theory of music is the first substantial knowledge one acquires from the inexhaustible art of music. It is crucial to establish a suitable starting point that will provide motivation and inspire young musicians towards the direction of knowledge and creation. For this purpose, after fifteen years of teaching music theory, I feel responsible to generously share my knowledge and experience with those who wish to explore the world of music. In this book, the student has the opportunity to both understand the theory and engage in practical exercises included at the end of each chapter. In addition to the established material of music theory, this series includes chapters presenting the musical instruments of the orchestra, in order to motivate the new musician to decide which instrument to pursue in their journey. It also includes chapters on proper music spelling, which serve as a launching pad for capturing one's personal compositional creation.