This introduction presents an overview of the concepts discussed in this book. The book presents a broad view of what mattered in the relationships between western and eastern Europe, and also between Europe, North Africa and the Middle East. It focuses on themes in economic, social governmental, ecclesiastical and cultural history, and discusses the government on a territorial or institutional basis. Governmentally, the period is broadly one of progress within western Europe in the sense that many lordships and kingdoms grew together in solidarity and developed a stronger sense of community. Royal government in France and England was immeasurably stronger at the end of the eleventh century, but in Germany, the position of the monarchy was more ambiguous and complex. The eleventh and twelfth centuries are the time when Romanesque art and architecture reached their zenith in all parts of western Europe; the twelfth is the century when the Gothic style began to flourish in the north.