This book provides an overview of high entropy alloys, explaining all the basics of this new class of materials that emerged at the beginning of the 21st: It begins with the basics of the manufacturing methods of high entropy alloys and discusses the mechanical properties and deformation mechanisms of high entropy alloys. Then the book addresses the stability of these alloys and explores the prospects of high entropy alloys for applications. This book is intended as an introduction for physicists and materials scientists who need to become familiar with high entropy alloys.