The first of its kind, this book is a systematic compilation of current knowledge of mechanics and reliability of flexible magnetic media. Chapter 1 presents the brief descriptions of physics of magnetic recording, magnetic storage systems and manufacturing processes of magnetic media. Chapter 2 presents a brief description of manufacturing processes of poly (ethylene terephthalate) films commonly used as flexible media substrate, and physical and chemical properties of the PET films and coated magnetic media. Chapter 4 presents analytical predictions of stresses in wound magnetic tapes and flexible disks. In Chapter 5, long-term reliability problems of magnetic tapes encountered during storage and use are discussed; their descriptions, mechanisms and methods of preventing them are presented. In Chapter 6, long-term reliability problems of flexible disks encountered during storage and use are discussed. Viscoelasticity theories presented in this book are very general and are applicable in systems other than magnetic-storage ones.This book is intended for three types of readers: graduate students of magnetic recording, the research worker who intends to become active in this field, and the practicing engineer who has encountered a reliability problem and hopes to solve it as expeditiously as possible.