There is no single definition for terrorism in international law or among scholars (Neumann, 2009). However, to simplify the discussion for this review, we conceptualise terrorism as 鈥渢he use of indiscriminate violence against non-combatants by non-state actors with the purpose of generating fear in order to signal and advance particular sociopolitical objectives... [which also aims] to intimidate a larger audience beyond those directly targeted with violence鈥� (Wilner and Dubouloz, 2010, p. 33). Most definitions such as this consider terrorism as violence committed by non-state actors (see the Global Terrorism Index, 2014). However, many scholars recognise the reality that governments also instigate terrorism when they carry out military attacks with the knowledge that civilians will be harmed (Kundnani, 2015; Naim and James, 2005). While we acknowledge this perspective, our review focuses primarily on violence carried out by non-state actors attempting to undermine governments.

It is important to note that terrorists may also work for what they imagine to be a common good or a moral cause. Terrorism is set apart from other kinds of violence by the terrorist鈥檚 belief in their moral superiority (Davies, 2009). Therefore, 鈥渟ince they often target civilians, terrorists lack moral strictures against the use of violence鈥� (Lake, 2002, p. 17). Spaces of terror are not limited to a momentary act of political violence like a car or suicide bombing where there is the destruction of property or loss of life (Ayinde, 2009). The act of a single terrorist can have a wide impact with long-term effects.