This is an open access title. It is made available under a Creative Commons Attribution-Non Commercial-No Derivatives 4.0 International licence. It is available to read and download as a PDF version on the Oxford Academic platform. There are more than ten thousand particle accelerators in the world from the linear accelerators used for cancer therapy in modern hospitals to the giant 'atom-smashers' at international particle physics laboratories used to unlock the secrets of creation. Many scientists and engineers spend their lives designing, constructing, and operating these machines - yet few universities include the subject of particle accelerators in their curricula. The few courses that do exist and the summer schools run by the big accelerator laboratories lack a simple introduction which covers the essentials of the subject for the many who need to learn how these machines work. This book fills that gap and takes the reader through each of the aspects of a modern accelerator giving enough information to unlock the door to the subject but does not overload the understanding with mathematics. Anyone with a general interest in modern technology based on a fascinating variety of physics and engineering will find much of interest in this book.