This introduction presents an overview of the key concepts discussed in the subsequent chapters of this book. The book is about the links between English witchcraft and the Devil in popular pamphlets. It focuses on the emotional interactions between witches and devils and a witch's supposed motivations for succumbing to Satan and performing witchcraft. Ideas of demonic copulation, sabbaths and devil worship were all notable features of witchcraft pamphlets well before Matthew Hopkins, and continued to be so well after his death. The book highlights the close association between the Devil, witches and fear throughout the early modern period and demonstrates how witchcraft pamphlets do not present one view of the Devil but actually contain many different beliefs. It also explores the diabolical nature of the familiar and examines the role of familiars in witchcraft pamphlets. The book looks at where familiars came from, what they did, what form they took and how they entered into pacts with witches.