The aesthetic industry has led the development and progress in different treatment methods of melanin-related conditions. However, it was rare to find a treatment method that was based on the understanding of melanin's life cycle. Because the melanin treatment is based on the destruction of the melanocytes, different complications have been reported after the treatment. The purpose of this book is to provide a better understanding of melanin's life cycle in order to address those complications. Using the common understanding of the role and function of melanin in each organ, This book will present the mechanism about the inherent function of melanin in our body, and will also re-address the role and life cycle of melanin in the skin and the concept and clinical usages of today's popular high frequency devices, theory of the photon-based treatment from energy-based devices for melanin destruction, such as light and laser, and the understanding of their mechanism. Additionally the book introduce the treatment and guidelines of melanin-related conditions, such as melasma, PIH, hyperpigmentation and hypopigmentation after the Atopic contact dermatitis.