The book also traces the substantial expansion in numbers both of sovereign states and international and regional organizations, and features detailed chapters on diplomatic privileges and immunities, diplomatic missions, as well as consular matters, treatymaking and conferences. The volume also examines alternative forms of diplomacy, from the work of NGOs to the use of secret envoys, and interrogates the interaction between intelligence agencies and commercial security firms. It also discusses the impact of international terrorism and other violent non-state actors on the life and work of a diplomat. Finally, in recognition of the speed of changes in the field over the last twenty years, it includes updated chapters on human rights and public/digital diplomacy by experts in their respective fields.