Quakers are distributed widely around the globe, and they experience many of the tensions of the broader church. Quakerism has changed as it has spread around the world. Early Quakers saw themselves as returning to the roots of Christianity as it may have been before the development of church institutions. This introduction presents an overview of the key concepts discussed in the subsequent chapters of this book. The book introduces Quakerism with a series of short examples of Quaker work in the world outside the confines of their meetings and churches. It explores the first 50 years of Quaker faith and practice in England and its spread to English colonies in the New World. The book traces the spread of the Society of Friends through the influence of Quaker writings, evangelism, and missionary work in Africa and South America since the early twentieth century.