Book excerpt: This book identifies and explains the functional and ideational boundaries regarding what states and Private Military and Security Companies (PMSCs) both do and possess regarding land power, sea power, and air power. Whereas the mercenaries, privateers, and chartered companies of years past held similar characteristics to state military forces, the PMSCs of today are dissimilar for two reasons: a conventional forces norm amongst states and a state proclivity towards the offensive. These factors reveal both the limitations of and the possibilities for contemporary security privatization. This volume is ideal for civilian and military practitioners and students wishing to develop a detailed understanding of what the private military and security industry has to offer and why it is structured the way it is.