When I started in magnetic recording nearly fifty years ago, it was easy to perceive the common sense of it. There was very little mathematics and every new finding was a source of wonder. I have tried to recapture this spirit with simple explanations, while maintaining a high density of infonnation and cov ering the entire field. This book introduces a novice to magnetic recording and its many branches. It includes reference data for designers and users. Each chapter stands by itself; no prerequisites are essential. For a quick survey, the equations and worked out examples can be disregarded. The magnetic recording art is changing so rapidly that new advances are announced almost every month. These are properly covered by journal articles and manufacturers' catalogs. This book will fulfil its purpose if it gives a back ground for easily comprehending the new advances. I have included subjects and devices not found elsewhere, and some unconventional viewpoints. I would welcome comments from readers. To Jay McKnight I am deeply grateful for important suggestions and helpful comments. I appreciate also the help of BASF, John Boyers, Joseph Dundovic, Charles Ginsburg, Peter Hammar, Yasuo Imaoka, Hal Kaitchuk, Otto Kornei, Harold Miller, Jack Mullin, Jim Novak, Lenard Perlman, Carl Powell, Sidney Rubens, John Shennan, Shigeo Shima, Heinz Thiele, Yoshimi Watanabe and many others; and to my daughter Ruth for typing.