ABSTRACT
This chapter focuses on a bit of semantics and defines the relation between the words threat, vulnerability and risk. The word threat is itself the subject of a semantic confusion since it designates both the threat-as-agent, these adversaries we fear, and the threat-as-action, that is an event, a bombing, a kidnapping or a plane hijacking. Threats have an aura of unpredictability and mystery that makes it uncannily fascinating. Threats are mysterious. Parts of some threats are obvious, most of their components are elusive. Threats are everywhere and risk, even when minimal, is never really far away. Risk is about probabilities. Threat is about actions and agents. Studying the nature of threat means listing and defining the threat agents or actors such as terrorists, activists, criminals, saboteurs, vandals and disgruntled employees. Those threat agents are divided into three categories: external or outside threat, internal or insider threat and colluding threats.
