Every nation has to deal with its state survival. Among the many aspects of security needed for the protection of the State is national security which has a broad coverage. Without national security, the economic, social, political, diplomacy and military interest of the nation will be all in peril. This book provides the fundamental concepts of the facets of national security and its domains. It gives an overview of national security which encompasses the basic knowledge on the nation’s capability to deal with internal and external threats as well as its position to face global challenges.