The essence of terrorism is the intent to induce fear in someone other than its victims to make a government or other audience change its political behavior. Terrorism is common practice in insurgencies, but insurgents are not necessarily terrorists if they comply with the rules of war and do not engage in those forms of violence identified as terrorist acts. While the legal distinction is clear, it rarely inhibits terrorists who convince themselves that their actions are justified by a higher law. Their single-minded dedication to a goal, however poorly it may be articulated, renders legal sanctions relatively ineffective. In contrast, war is subject to rules of international law.
Terrorists recognize no rules.
No person, place, or object of value is immune from terrorist attack. There are no innocents. This situation did not always prevail. Throughout history, extremists have practiced terrorism to generate fear and compel a change in behavior. Frequently, terrorism was incidental to other forms of violence, such as war or insurgency.