This introduction presents an overview of the key concepts discussed in the subsequent chapters of this book. The book looks at the demilitarization and neutralization of Aland as a long-standing regime intended to limit war. It introduces such trends and discourses of militarization, while various forms of regional security co-operation. The book dedicates to the law of the sea rules and considerations affecting the Aland Islands, in particular issues of rights of passage. It also looks at various forms of security co-operation affecting the Aland Islands. The book explains, possible exceptions to this fact, including the Swedish expedition of 1918, shortly after Finland's proclamation of independence, the dangerous and uncertain situations involved in both Russian revolutions and the manifold outcomes of the First World War. It describes legal framework pertaining to the Aland demilitarization and neutralization and raises questions about its continuity, its oversight and about the effects of new technology.